Sealed us (σφραγισαμενος ημας). From σφραγιζω old verb, common in LXX and papyri for setting a seal to prevent opening (Daniel 6:17), in place of signature (1 Kings 21:18). Papyri examples show a wide legal use to give validity to documents, to guarantee genuineness of articles as sealing sacks and chests, etc. (Deissmann, Bible Studies, p. 238; Moulton and Milligan's Vocabulary).

The earnest of the Spirit (τον αρραβωνα του πνευματος). A word of Semitic origin (possibly Phoenician) and spelled both αραβων and αρραβων. It is common in the papyri as earnest money in a purchase for a cow or for a wife (a dowry). In N.T. only here; 2 Corinthians 5:5; Ephesians 1:14. It is part payment on the total obligation and we use the very expression today, "earnest money." It is God, says Paul, who has done all this for us and God is Paul's pledge that he is sincere. He will come to Corinth in due time. This earnest of the Spirit in our hearts is the witness of the Spirit that we are God's.