Who said he was going to kill Baasha's family (and posterity) and feed them to the dogs and birds?

The Lord

Then the word of the LORD came to Jehu the son of Hanani against Baasha, saying ... I will take away the posterity of Baasha ... Him that dieth of Baasha in the city shall the dogs eat; and him that dieth of his in the fields shall the fowls of the air eat. 1 Kings 16:3-4