Timotheus - Timothy. He was a proper person to send there to visit the churches, as he had been there before with Paul, when they were established, Acts 16:3; Acts 17:14.
And Erastus - Erastus was chamberlain of Corinth (Romans 16:23), or, more properly, the treasurer of the city (see the notes on that place), and he was, therefore, a very proper person to be sent with Timothy for the purpose of making the collection for the poor at Jerusalem. Paul had wisdom enough to employ a man accustomed to monied transactions in making a collection. On this collection his heart was intent, and he afterward went up with it to Jerusalem. See 2 Corinthians 8:9, and notes on Romans 15:25-26.
Stayed in Asia - At Ephesus.
For a season - How long is uncertain. He waited for a convenient opportunity to follow them, probably intending to do it as soon as they had fully prepared the way for the collection. See Paley’s Horae Paulinae, p. 1, chapter 2.