Satan and his forces always watch for our weakest point.

Let us find out what that point is.

What is the weak part of our defences?
Is it selfishness?
Is it pride?
Is it prayerlessness?
Is it temper?
Is it an unkind spirit?
Whatever it is by which we are most easily led astray, that is our weak spot, and there we ought to set a double watch.

David had his weak spot, and he knew it: unguarded, hasty words were ever coming out of his mouth, but he found out the weak point in his defences, and there he set a strong and powerful guard.

He called upon God Himself to keep out the enemy at that weak place: 'Set a watch, O Lord, before my mouth.