Easton's Bible Dictionary (1897)/Ambassador
Ambassador, in the Old Testament the Hebrew word Tsir, meaning "one who goes on an errand", is rendered thus (Joshua 9:4; Proverbs 13:17; Isaiah 18:2; Jeremiah 49:14; Obadiah 1:1). This is also the rendering of Melits, meaning "an interpreter", in 2 Chronicles 32:31; and of Malak, a "messenger", in 2 Chronicles 35:21; Isaiah 30:4; 33:7; Ezek. 17:15. This is the name used by the apostle as designating those who are appointed by God to declare his will (2 Corinthians 5:20; Ephesians 6:20).
The Hebrews on various occasions and for various purposes had recourse to the services of ambassadors, e.g., to contract alliances (Joshua 9:4), to solicit favours (Numbers 20:14), to remonstrate when wrong was done (Judges 11:12), to condole with a young king on the death of his father (2 Samuel 10:2), and to congratulate a king on his accession to the throne (1 Kings 5:1).
To do injury to an ambassador was to insult the king who sent him (2 Samuel 10:5).