John Gill Commentary 1 Kings 11:10

"and had commanded him concerning this thing, that he should not go after other gods: but he kept not that which Jehovah commanded." — 1 Kings 11:10 (ASV)

And had commanded him concerning this thing that he should not
go after other gods
Which is another aggravation of his sin, because it was against an express command of God, and was particularly given to him, and he was warned to observe it and threatened with evil if he should break it:

but he did not keep what the Lord commanded :
see (1 Kings 9:5–7) .