Q. Samuel said to Saul that he should wait for him in Gilgal for seven days for him to offer sacrifices for the favor of God before a battle. After Saul disobeyed Samuel told him that if he had obeyed, “the Lord would have established your kingdom over Israel forever.”
However, we learn in Genesis, when Jacob blessed his sons, that “the scepter will not depart from Judah, nor the ruler’s staff from between his feet, until he to whom it belongs shall come and the obedience of the nations shall be his.” Saul was not from Judah. So how was that going to happen, if the Lord had established his kingdom forever?
The answer to your question is in the meaning of the word that many English versions translate as “forever.” As I explain in this post, the word ‘olam means “to indefinite futurity,” that is, “for as far into the future as anyone can imagine.” Samuel was telling Saul that God would have established a dynasty for him that would last a good long time, with no one being able to envision when or how it would end. That is not the same as saying that it would never end, so that the prophesied ruler from the tribe of Judah would never come.
Good Question 