Albert Barnes Commentary Psalms 89:24

"But my faithfulness and my lovingkindness shall be with him; And in my name shall his horn be exalted." — Psalms 89:24 (ASV)

But my faithfulness and my mercy shall be with him - I will at the same time be faithful to him, and merciful. These attributes of my nature shall be always attendant on him, as if they were his own.

And in my name - By me; or, He, acting in my name and in my cause, shall be exalted.

Shall his horn be exalted - See the notes at Psalms 89:17.