Which knoweth the heart (kardiognwsth). Late word from kardia (heart) and gnwsth (known, ginwskw). In the N.T. only here and Acts 1:24 which see. Giving them the Holy Spirit (dou to pneuma to agion). And before their baptism. This was the Lord's doing. They had accepted ( Acts 11:18 ) this witness of God then and it was true now of these other Gentile converts.