Shammah is the name of the third of David's mightiest men
His noted exploits including the spirited defence of a lentil field! The parallel reading (1 Chrons 11:13) tells us:
Eleazar defended a barley field and that he was not on his own. No contradiction here

Both crops may have occupied the same field: Eleazar and friends defended the barley end…Shammah was busy defending the lentil side

At first glance, it seems to have been a storm in a tea cup!
Imagine fighting over a field full of crops!
 Did they beat each other over the head with stalks? Did they use pea shooters? :-)
But the incident, far from being frivolous, not only gets recorded in the Book/God, but merits a high mention. Nothing useless here. Nothing trivial in the Sacred Volume. Humour…no triviality.
3 important lessons to be learnt:
 
1) THE ENEMIES OF GOD WILL SEEK TO SUSTAIN THEMSELVES BY TAKING THE PROVISIONS OF GOD'S PEOPLE:
Marginal reading: Philistines were gathered together to forage

A/ The enemies/God (rep: by the Philistines) cannot fight without being sustained i.e. they are not invincible
Sometimes the enemy comes in like a flood:
Sweeping - powerful - overpowering etc.,
We seem so helpless - outnumbered/outmanoeuvred/outrun
We say: Can I really fight this enemy? Can I really win?
Is it possible to live a spiritual life for Jesus Christ in an age like this where sin is so rife/acceptable?
Can I walk apart?

The enemies/God are not as powerful as we/they might think
Even the Devil himself - although never underestimate him - but even the devil cannot do everything he would like to do
Devil can be defeated by the Christian. James 4:7 Resist/flee
Devil often has to withdraw due to his great limitations

B/ In order to further their own agenda, the enemies/God will come like the Philistines to feed of God's people.
They want our lentils/barley
Let's see how this worked out/other passages/Bible:

[i] In Galatians 2:4 And that because of false brethren unawares brought in, who came in privily to spy out our liberty which we have in Christ Jesus, that they might bring us into bondage:
Our doctrine is an offence to every false teacher/cultist
They want to remove it and bring us into belief of their doctrine
Our liberty (which is not a license/sin) is based on our doctrine
These professing brethren will come unawares (Creep in: Jude 3) and do so privily and steal away our spiritual food
And so Paul's epistle/Galatians is a no holds barred no nonsense piece/writing: 1:8 etc.,

[ii] Seek to take not only away our doctrine (and its liberty) but also come to steal away our people
The thief cometh not but to steal… (John 10:10)
Happened in NT times: For there are many unruly and vain talkers and deceivers, specially they of the circumcision:  Whose mouths must be stopped, who subvert whole houses, teaching things which they ought not, for filthy lucre's sake. (Titus 1:11)
Many good causes out there, founded by godly men, which were hijacked by the apostates/ecumenists etc.,
Entire congregations have been lost because secret Philistines came in and subverted them

C/ Maybe we think/ourselves: Well many of the cults are pretty active. Do all the hard work themselves etc., get their meetings going by their own efforts etc., and pretty much leave us alone
That might be so…but only to a point
All things are not equal (We're right and they're horribly wrong)
and therefore they are stealing the potential converts which God has instructed us to chase after
They're still Philistines! They are trespassing on our ground
They are coming for our crops. The lentils/barley come through the sowing/seed - the seed is the word/God.

2) GOD'S PEOPLE ARE OFTEN INCLINED TO LET THEM DO SO:
With the exception/Shammah  - all fled when Philistines came (v11)
Why was it then and why is it now among God's people that there is no stomach for a fight?
Whatever happened to war a good warfare?
Here's some thoughts:

A/ We have listened to the enemy's propaganda
During the war, it was declared illegal to listen to Lord Haw-haw because he sought to sap the morale of the people
Not considered a laughing matter/mere distraction by the authorities
 We have allowed the enemy to convince us of his absolute strength
We have seen the war paint and heard the battle cry and our blood has curdled, our hands have shook with fear
And we have been prepared to surrender up that field which we have sown and expect to reap from.

B/ We have underestimated our own fighting capacities
Lord Haw-haw not only boasted of Germany's strength, but he denigrated and derided the Allies capacity to resist
Battleships were sinking daily? Aeroplanes being shot down etc.,
It is ever the devil's aim to strip us of the armour/God
To undermine our confidence in the Bible/prayer/evangelism

C/ Raising a voice at least/protest brings us to the attention of a sneering world and (shame to say so) a contented church
Not hard to be a fanatic today! Not hard to considered right wing!
Show any concern for the way things are drifting
(More like steamrollering) and you become a scare-monger
Evangelical people whose doctrine/sound will shun you/oppose you

Try raising a voice against the onward march/RC Church
Try taking on modernism as it appears in evangelical denominations
Use the term "neo-evangelicalism" and name names
Have a go at Billy Graham's ecumenical evangelism  
Have a go at worldliness in fundamental churches
Questionable music/questionable dress standards/questionable pastimes like dancing/Sabbath defilement and people who are otherwise sound will oppose you and brand you as an unloving fanatic  

Do you think Shammah here is being set forth as a fanatic?
Should I be warning you in this message to avoid mindset of this man?
What would you feel if I said: "All the other Israelites ran away, but there's always one fly in the ointment and here it's this awkward, time warped Puritan wannabe called Shammah who lacked love?"
Would it sound right if I berated him for upsetting the Philistines?

D/ Maybe some/folk thought: I could lose big time if I fought the Philistines. I could lose a limb! I could lose my life!
Not unwarranted thinking. When you battle for God, you could lose plenty as far as this world is concerned:
Already mentioned your reputation. Could lose money/business etc.,
Promotion. Gain physical hurt or death itself. What of your gains?
Think of the treasure laid/Heaven where treasure really matters. Think of the glory that you stood for the Crown Rights of King Jesus
 
E/ Sad as it is that many/God's people have no stomach for the fight - never been taught their responsibilities as soldiers/Jesus Christ - we are not to follow their example. Be a Shammah

3) GOD WILL GIVE VICTORY TO THOSE WHO REFUSE IN ANY WAY TO SUSTENANCE HIS ENEMIES:
A/ Shammah wasn't compromising. Plenty/fields of barley/lentils etc.,
Give them nothing! Fight them the whole way! Starve them out!

B/ This field/lentils:in the Promised Land. God's acre…not Shammah's and certainly not the Philistines. What else could he do but fight?

C/ So he stood midst/ground. Young: He stationed himself…
If he was going/perish…he was going to perish/principles. I like that! Not popular to be a 6 day creationist. Justification by faith alone man. To believe the Bible is literally God's word. Separatist etc.,  
Not popular to say "no" in school/street/workplace to certain things
But I would rather perish there, defending my God given principles than to surrender them up just to keep in with the crowd

D/ He defended the ground. He attacked and slew the enemies/God and the little patch/ground was kept safe. The enemy came to get food/belly…got Shammah's sword instead. Better dieting than dying!

E/ God stood with this man. Like Eleazar (v10) the Lord through him wrought a great victory. We really do lack faith if we just see the Philistines or we just see the professing people/God scampering away. We really do lack faith if we cannot see Jesus Christ building His church and the gates/hell unable to stand it

G/ Consider this/closing. Shammah believed God. Believed the promises/God esp. 1 Samuel 2:30 Believed it in a practical way
Not a barrack ground soldier - but a battleground soldier
Had a job to do. Believed God would bless his stand and so he stood
Doubtless he prayed etc., took no unnecessary risks etc., but he did venture out and he came home rejoicing that he did
Will you? In your home/work/school/college? You can't lose if you do