Paul voiced in his first epistle to Timothy thanks for his own salvation and ministry ( 1 Timothy 1:12). In this second epistle he began with thanks for Timothy"s salvation and ministry. [source][source][source]
Paul"s reference to his forefathers (God-fearing Jewish believers who lived before Christ"s death) seems unusual. However throughout this epistle Paul looked backward into the past and ahead into the future, when he would no longer be alive. This reference reveals that Paul regarded his own ministry as part of the continuation of God"s great ongoing plan of the ages. He was one of the faithful throughout history that have loyally served God sincerely, with a "clear conscience."[source]
"These two themes-association with Paul and a spiritual heritage-form the basis of Paul"s encouragement in the first half of the epistle and are woven throughout the second half. They provide a personal look into Paul"s heart and reveal his love and concern for his good friend Timothy." [1][source]
Paul undoubtedly prayed for Timothy often, and when he did he thanked God for his friend. Timothy had been one of Paul"s closest associates, and he was evidently still laboring in Ephesus (cf. 2 Timothy 4:19-20), the city where Paul had spent so much time. Paul had plenty of time to pray since he was again in prison (cf. 2 Timothy 4:9; 2 Timothy 4:16; 2 Timothy 4:21). It is not only good to pray for individuals, but it encourages them when we tell them that we do, as Paul did here. [source][source][source]
Even though Paul rejoiced continually his life was not "filled with joy" when he wrote this letter. He longed for Timothy to visit him. Evidently when they had parted last-perhaps the event referred to in 1 Timothy 1:3 -Timothy had taken their separation very hard. A reunion would encourage Timothy too. [source][source][source]
"One of the fascinating aspects of Pauline studies is the very real humanity of this man of God. Paul was a stalwart soldier, but he had a tender heart." [2][source]