Passage Numbers 23:19
Numbers 23:19 says God is not a man that he should change his mind. Yet 1 Samuel 15:35 says the LORD regretted that he had made Saul king, and Exodus 32:14 says he relented from the disaster he had spoken of. The argument treats these as a direct clash about whether God ever changes course.
God is not man, that he should lie, or a son of man, that he should change his mind. Has he said, and will he not do it? Or has he spoken, and will he not fulfill it?
Numbers 23:19
And Samuel did not see Saul again until the day of his death, but Samuel grieved over Saul. And the LORD regretted that he had made Saul king over Israel.
1 Samuel 15:35
And the LORD relented from the disaster that he had spoken of bringing on his people.
Exodus 32:14
Source: see Credits and references (no. 14, p. 10).