In the second, when he wrote to the Corinthians to send Saint Timothy to him in peace (see 1 Cor 16:11).
In the first case we get this thought: Zenas and Apollos were with Saint Paul. Needing to send them somewhere for the work of preaching, perhaps to Achaia, he directed them there through Crete because of circumstances.
He writes to Titus that he should not detain them, but conduct them farther quickly, supplying them with everything necessary.
In this case one may suppose that the Epistle to Titus was sent with them, or that they were sent with the bearer of the epistle.
Perhaps this epistle was even written because they were being directed by this route.
In the second case, the thought is this: Zenas and Apollos were in Crete and labored there in the preaching of the Gospel even before Saint Paul passed through and arrived there.
When Saint Paul departed from Crete, he left them there to continue the work of preaching together with Titus.
Now, however, needing them for the same work of preaching in the region where he himself was, he writes to Titus to send them to him quickly, before Titus himself is summoned.
This was to be done immediately upon receiving this epistle.
"And let nothing be lacking to them." Supply them with everything necessary: food, clothing, and a certain sum of money for travel expenses (see blessed Jerome, Oecumenius, and blessed Theophylact), so that they have no lack in anything.
Zenas shepherded the Church of Christ in Diospolis. His commemoration is September 27. He is numbered among the Seventy.
Apollos, according to Jerome, was bishop in Corinth. But the calendars write that he was bishop in Smyrna before Saint Polycarp. He is numbered among the Seventy. His commemoration is September 10 and December 8.