It seems to me that vv. 11, 35 speak of God repenting, relenting or regretting from a human point of view, while v. 29 unambiguously declares that He, in fact, does not repent, relent, or have regret. J.P. Lange comments on v. 10, saying, “The Repentance Of God is the anthropopathic [attribution of passions to God] expression for the change of the divine procedure into the opposite of what the holy and righteous will of God had determined under the condition of holy and righteous conduct by men, when on man’s side there has been a change to the opposite of this condition without repentance.” Saul had disobeyed the Lord, therefore, the Lord rejected Saul as king. As He said to Eli, the same is true here, “Far be it from me, for those who honor me I will honor, and those who despise me shall be lightly esteemed” (1Sam. 2:30). Saul had dishonored the Lord and therefore, the Lord was sorry and regretted (from our perspective) for making him king. As John Piper notes:
the Repentance Of God is his expression of a different attitude and action about something past or future—not because events have taken him off guard, but because events make the expression of a different attitude more fitting now than it would have been earlier. God’s mind “changes,” not because it responds to unforeseen circumstances, but because he has ordained that his mind accord with the way he himself orders the changing events of the world.
Since Saul had disobeyed and dishonored the Lord, therefore, he is rejected by the Lord Who made him king. Moreover, the fact that this expression in vv. 11, 35 does not denote a surprise in God of what happened or a change of mind is confirmed by His promise to Judah. In Genesis 49:8-11, it is to Judah that the scepter is promised, and not to Benjamin whose descendant Saul was. Therefore, Saul had to be rejected so that the promise to Judah could be fulfilled in David (and ultimately in the Greater David). God knew and had promised that the kingdom would belong to Judah, therefore, this makes it all the more necessary for Saul to be rejected and a descendant of Judah to sit upon the throne. Had Saul been obedient then the kingdom would have been established in his name, but he was not because his line was not promised to have the scepter.
The last passage which I want to look at is the intercession of Moses and the “repentance” of God in Exodus 32. Moses has gone up to Mt. Sinai to receive the Decalogue from the hand of God. He has been there forty days and forty nights and then God tells him, “Go down, for your people, whom you brought up out of the land of Egypt, have corrupted themselves” (Ex. 32:7). Notice how God distances Himself from the idolatrous Israelites. He does not say “My people whom, whom I brought up…,” but rather He associates the people with Moses because of their sin. Then we read of God’s determination to destroy Israel in these words:
Exod 32:9-10 And the LORD said to Moses, “I have seen this people, and behold, it is a stiff-necked people. 10...