What is the meaning of "Ashurenu Atah Sevavunu"?
Rashi: Now, the enemy surrounded our footsteps, and "they put their eyes to spread out in the land." Also refer to 17:1:1:1.
Radak: When they will know our steps (location), they will immediately come to surround us. `3. Malbim: Until now, our steps were affirmed. Now, their eyes surround us. I.e. Sha'ul says that David and his men put their eyes to spread out in the land, they surround our steps. They send their eyes in the entire land to investigate everything, to find a pretext to rebel against me, and seize kingship and authority in the land.
Why is it written Sevavuni, and we pronounce it Sevavunu?
Radak: The Kesiv refers to David himself, for he is primary. The pronunciation refers to him and his friends who gathered with him when he fled Sha'ul.
Why did he say "Eineihem Yashisu Lintos ba'Aretz"?
Radak: They will put their eyes to our path to spread their net in the land to trap us.
Malbim: Refer to 17:11:1:3.
