Albert Barnes Commentary Galatians 1:5

"to whom [be] the glory for ever and ever. Amen." — Galatians 1:5 (ASV)

To whom be glory, etc. Let him have all the praise and honour of the plan and its execution. It is not uncommon for Paul to introduce an ascription of praise in the midst of an argument. (See the notes on Romans 1:25.)

This practice results from the strong desire he had that all glory should be given to God—a desire that also showed his belief that all blessings had their origin in God, and that God should always be acknowledged.