John Gill Commentary Philemon 1:3

"Grace to you and peace from God our Father and the Lord Jesus Christ." — Philemon 1:3 (ASV)

Grace to you and peace, from God
Which is the same form of salutation used in the other epistles; (See Gill on Romans 1:7) for though this epistle is but a very small one, yet it is introduced in the same form as the larger epistles are; and has an inscription in the former verse, a salutation in this, and a preface in the three following.