kardiognōstēs

(Translation from NRSV with a few modifications for a more literal meaning)

Acts

1: 24

Then they prayed and said, "Lord, you heart-knower (kardiognōstēs) of everyone. Show us which one of these two you have chosen

15: 8

And God, the heart-knower (kardiognōstēs), testified to them by giving them the Holy Spirit, just as he did to us;