Surely in vain the net is spread in the sight of any bird.

The proud have hid a snare for me, and cords; they have spread a net by the wayside; they have set gins for me. Selah.

The bird alighteth not on the spread net when it beholds another bird in the snare. Take warning by the misfortunes of others, that others may not take example from you.

Use not vain repetitions

For yourselves, brethren, know our entrance in unto you, that it was not in vain: / But even after that we had suffered before, and were shamefully entreated, as ye know, at Philippi, we were bold in our God to speak unto you the gospel of God with much contention.

And again, The Lord knoweth the thoughts of the wise, that they are vain.