John Gill's Bible Commentary
Ver. 7. Therefore, brethren, we were comforted over, you , etc.] Or in you, as the Vulgate Latin version; or from you, as the Arabic; or by you, as the Syriac; or for you, as the Ethiopic; that is, on account of them, either by what they had heard was in them, or had heard from them. This gave abundant consolation in all our affliction and distress : which they met with at Corinth, where the apostle laboured with his own hands, and ministered to his own, and the necessities of others, and was greatly opposed, reproached, and persecuted; (see Acts 18:3,6,9,10,12), but the news of the good estate and condition the Thessalonians were in, was a great relief and comfort to him, particularly their faith: by your faith : by the report of it, that it grew exceedingly, and that they walked in the truth; (see 1 John 5:4). The Alexandrian copy reads, in all your distress and affliction, and by your faith.
Matthew Henry Commentary
Verses 6-10 - Thankfulness to God is very imperfect in the present state; but on great end of the ministry of the word is to help faith forward. Tha which was the instrument to obtain faith, is also the means of increasing and confirming it, namely, the ordinances of God; and a faith cometh by hearing, so it is confirmed by hearing also.
Greek Textus Receptus
δια 1223 τουτο 5124 παρεκληθημεν 3870 5681 αδελφοι 80 εφ 1909 υμιν 5213 επι 1909 παση 3956 τη 3588 θλιψει 2347 και 2532 αναγκη 318 ημων 2257 δια 1223 της 3588 υμων 5216 πιστεως 4102
Vincent's NT Word Studies
7. Affliction (anagkh). Rev. distress. The derivation from agxein to press tightly, to choke (Lightfoot, Ellicott) is doubtful. In the sense of urgency, distress, seldom in Class. See 1 Cor. vii. 26; 2 Corinthians vi. 4; xii. 10; Luke xxi. 23.
Robertson's NT Word Studies
3:7 {Over you} (ef' humin). epi with the locative, the basis on which the "comfort" rests. {In} (epi). Locative case again with epi. {Distress} (anagkei). {Physical necessity}, common sense in late Greek, choking (agcw, angor), and {crushing} trouble (qliyis, qlibw).