en_tn/1sa/10/21.md

the clan of the Matrites was chosen ... Saul son of Kish was chosen

This can be translated in active form. It is probably best not to say how the people knew whom Yahweh had chosen. Alternate translation: "Yahweh chose the clan of the Matrites ... Yahweh chose Saul son of Kish" (See: rc://en/ta/man/jit/figs-activepassive)