commonly a ring engraved with some device (Genesis 38:18, 25)
Jezebel “wrote letters in Ahab's name, and sealed them with his seal” (1 Kings 21:8). Seals are frequently mentioned in Jewish history (Deuteronomy 32:34; Neh. 9:38; 10:1; Esther 3:12; Song of Songs 8:6; Isaiah 8:16; Jeremiah 22:24; 32:44, etc.). Sealing a document was equivalent to the signature of the owner of the seal. “The use of a signet-ring by the monarch has recently received a remarkable illustration by the discovery of an impression of such a signet on fine clay at Koyunjik, the site of the ancient Nineveh. This seal appears to have been impressed from the bezel of a metallic finger-ring. It is an oval, 2 inches [5.08 centimeters] in length by 1 inch [2.54 centimeters] wide, and bears the image, name, and titles of the Egyptian king Sabaco” (George Rawlinson, Historical Illustrations of the Old Testament, 1871, p. 46). The actual signet-rings of two Egyptian kings (Cheops and Horus) have been discovered. (See SIGNET.)
The use of seals is mentioned in the New Testament only in connection with the record of our Lord's burial (Matthew 27:66). The tomb was sealed by the Pharisees and chief priests for the purpose of making sure that the disciples would not come and steal the body away (ver. 63, 64). The mode of doing this was probably by stretching a cord across the stone and sealing it at both ends with sealing-clay. When God is said to have sealed the Redeemer, the meaning is, that he has attested his divine mission (John 6:27). Circumcision is a seal, an attestation of the covenant (Romans 4:11). Believers are sealed with the Spirit, as God’s mark put upon them (Ephesians 1:13; 4:30). Converts are by Paul styled the seal of his apostleship, i.e., they are its attestation (1 Corinthians 9:2). Seals and sealing are frequently mentioned in the book of Revelation (5:1; 6:1; 7:3; 10:4; 22:10).