John Gill Commentary 1 Kings 15:19

"[There is] a league between me and thee, between my father and thy father: behold, I have sent unto thee a present of silver and gold; go, break thy league with Baasha king of Israel, that he may depart from me." — 1 Kings 15:19 (ASV)

There is a league between me and you, and between my
father and your father
For though Hezion, if he is the same with Rezon, was an adversary to Israel in the days of Solomon, (1 Kings 11:25) , yet it seems his son was not, but was a confederate with the kings of Israel and Judah:

behold, I have sent unto you a present of silver and gold ;
taken out of the treasury of the temple and his own treasury:

come and break your league with Baasha king of Israel, that he may
depart from me ;
it was sinful in him to take the money out of the temple, to which it was dedicated; it was more so to make use of it to bribe an Heathen to break his covenant and alliance with another, in order to serve him; in which he betrayed great distrust of the Lord, and of his power to help him; which was the more aggravated, when he had had such a wonderful appearance of God for him against the Ethiopians, see (2 Chronicles 16:7 2 Chronicles 16:8) .