John Gill Commentary Philemon 1:8

"Wherefore, though I have all boldness in Christ to enjoin thee that which is befitting," — Philemon 1:8 (ASV)

Wherefore, though I might be much bold in Christ
Or use much freedom of speech in the name of Christ, as an ambassador of his, and great authority as his apostle, which was given him for edification:

to enjoin you that which is convenient ;
which became you as a believer in Christ, and a minister of the Gospel; which was your duty, and was obligatory upon you, agreeable to the doctrines of Christ; who taught men to love their enemies, to be reconciled to their brethren, that had offended them, especially when they repented; and therefore it was fit and proper that you should receive your servant again, since God had called him by his grace, and given him repentance for his sins:

upon this basis the apostle could have commanded you, as he did in other cases, (2 Thessalonians 3:6 2 Thessalonians 3:12) , but he chose not to address you in an authoritative way, but by way of entreaty, as follows.