Albert Barnes Commentary 2 Kings 10:15

"And when he was departed thence, he lighted on Jehonadab the son of Rechab coming to meet him; and he saluted him, and said to him, Is thy heart right, as my heart is with thy heart? And Jehonadab answered, It is. If it be, give me thy hand. And he gave him his hand; and he took him up to him into the chariot." — 2 Kings 10:15 (ASV)

Jehonadab belonged to the tribe of the Kenites, one of the most ancient in Palestine (Genesis 15:19). Their origin is unknown, but their habits were certainly those of Arabs. Because of their connection with Moses (see the note on Numbers 24:21), they formed a friendship with the Israelites, accompanied them in their wanderings, and finally received a location in the wilderness of Judah (Judges 1:16).

The character of this chief, Jonadab, is best seen in the rule he established for his descendants—a rule reportedly still observed today (Jeremiah 35:6–7). He seems to have strongly sympathized with Jehu’s actions and desired to lend the support of his authority, such as it was, to the new reign.

According to the Hebrew text, Jehu “saluted” (or blessed) Jehonadab. The Septuagint and Josephus, however, state that Jehonadab “saluted” (or blessed) the king. Furthermore, the Hebrew text reads: “And Jehonadab answered, It is, it is. Give me your hand. And he gave him his hand, and took him up to him into the chariot.” The English translators appear to have preferred the Septuagint, but the Hebrew account is more vivid.

Jehu was undoubtedly glad to have Jehonadab's support on his public entrance into Samaria. This ascetic figure had a reputation for sanctity, which would certainly make his companionship an advantage to the monarch whose reign was not yet secure.