1 Corinthians 4:17

For this cause have I sent unto you Timotheus
This is an instance of his care of them, concern for them and respect unto them; that he not only writes unto them, giving his best advice and counsel, promising to come unto them; but in the mean while sends Timothy to them, whose character is here given as one dear to him, and in all things trusty and faithful:

who is my beloved son;
so, in his epistles to him, he often styles him his son, his own son in the faith, his dearly beloved son; not that he was the instrument of his conversion, for he was a disciple of Christ before the apostle was acquainted with him; see ( Acts 16:1 ) but either because of his age, he being younger than he; or because of his great affection for him; and chiefly because, as a son with a father, he served him in the Gospel, ( Philippians 2:22 ) and since he was so familiar with him, and so much loved by him, it might reasonably be thought he full well knew his ways and methods of doctrine and practice.

And faithful in the Lord;
a faithful steward of the mysteries of grace; faithful in the Gospel of Christ, and to the souls of men; a faithful minister of the Lord's; one who had been tried, proved, and found faithful, and therefore might be trusted to, and depended upon:

who shall bring you into remembrance of my ways;
his way of preaching, and the doctrines he taught; and what should be the manner of life and conversation agreeably thereunto, and to his own; and all those rules and orders he gave for the discipline and management of the affairs of churches; all which he had formerly delivered to them, though they, through length of time, and the ministry of the false teachers among them, had greatly forgotten them: wherefore Timothy is sent, not to teach them new ways, nor, indeed, to teach at all, whose youth they might be tempted to despise; but only to put them in mind of what the apostle had formerly taught them: and which are recommended by their being such ways,

which be in Christ;
the doctrines he had preached among them, the sum and substance of them were Christ, and him crucified; the ordinances he had delivered to them were what he had received from Christ; and all the rules and methods he had proposed to them for the regulation of their conduct, and the management of their ecclesiastical affairs, were such as were agreeably to the mind of Christ, and tended to his glory; he took no step, nor proposed any to be taken, but in Christ, and for the good of his interest: and he adds,

as I teach everywhere,
in every church; the faith he delivered everywhere was one and the same; the Son of God, preached by him, was not yea and nay; the trumpet he blew always gave a certain sound; the rules prescribed by him, and orders he laid down, for the conduct of life, and government of churches, were exactly alike in all places; he taught no doctrines at Corinth, nor enjoined the observance of any rule, but what all other churches were taught and directed to; his plan of doctrine and discipline was the same everywhere.