The Lord grant unto him that he may find mercy of the Lord in that day: and in how many things he ministered unto me at Ephesus, thou knowest very well.
Paul asserts his apostolic authority not for Timothy's sake alone; Timothy already believed. He writes with these grand titles because he stands at death's door and means to seal his whole ministry with his blood, that the Church may know his doctrine comes from God Himself, not from a mortal man's opinion.
AI summary
Commenting on 2 Timothy 1:1-18
Having (Ti2 1:13, Ti2 1:14) exhorted Timothy to hold fast, I. He mentions the apostasy of many from the doctrine of Christ, Ti2 1:15. It seems, in the best and purest ages of the church, there were those that had embraced the Christian faith, and yet afterwards revolted from it, nay, there were many such.
Commenting on 2 Timothy 1:15-18
The Lord grant unto him that he may find mercy of the Lord in that day;.... In return for his diligent seeking till he found the apostle. By "mercy", he means the mercy of our Lord Jesus Christ unto eternal life; or that crown of righteousness and everlasting glory and happiness, which will be a grant from the Lord, or a free gift through Jesus...