John Gill Commentary 1 Kings 11:34

"Howbeit I will not take the whole kingdom out of his hand; but I will make him prince all the days of his life, for David my servant`s sake whom I chose, who kept my commandments and my statutes;" — 1 Kings 11:34 (ASV)

Howbeit, I will not take the kingdom out of his hand
Not any part of it, (1 Kings 11:12) ,

but I will make him prince all the days of his life ;
that is, he shall continue to hold the government of all the tribes so long as he lives:

for David my servant's sake, whom I chose, because he kept my
commandments and my statutes ;
see (1 Kings 11:12) , or was well pleased with, as the Targum; for keeping the commands of God from right principles, and with right views, is well pleasing to him.