‘For this reason I also, when I could no longer forbear, sent that I might know your faith, lest by any means the tempter had tempted you and our labour should be in vain.'
The change to the first person singular brings out how much he was moved by what he was talking about. He felt personally involved. He had heard about what they were going through, and was concerned about what effect it was having on their faith. So in the end he could not restrain himself. He had to know. That was why he had despatched Timothy in order to find out.
‘Lest by any means the tempter had tempted you.' Paul was very much aware that once a person became a Christian they became a prey of the Tempter. ‘By any means' reminds us that his methods are not restricted to persecution and affliction (compare Ephesians 6:12). But in context that was clearly to the fore. Paul saw the hand of the Tempter behind all attacks on Christians. He was encouraged in this by the words of Jesus Himself. Satan had desired to have them that he might sift them as wheat (Luke 22:31 compare Job 1-2). He had used tribulation to try to shake their faith, and persuade them to turn from Christ.
‘And our labour should be in vain.' The change to the subjunctive indicates that this was something mooted, not something believed. It had been a possibility that their labour might have been in vain, but Paul had hoped for better things, in which as it turned out he was justified. The word for labour suggests great effort. The ministry had not been an easy one, as indeed no ministry should be.