I Samuel 26:4 Midrash

וַיִּשְׁלַ֥ח דָּוִ֖ד מְרַגְּלִ֑ים וַיֵּ֕דַע כִּֽי־בָ֥א שָׁא֖וּל אֶל־נָכֽוֹן׃

David therefore sent out spies, and understood that Saul was come of a certainty.

Read midrashic interpretation of I Samuel 26:4: and classical rabbinic exegesis.