Adam Clarke on 2 Corinthians 8:19

Chosen of the Churches to travel with us - Χειροτονηθεις· Appointed by a show of hands; from χειρ the hand, and τεινω, to extend. This appointment, by the suffrage of the Churches, seems to refer more to St. Luke than any one else; unless we suppose he refers to the transaction, Act 15:40, Act 15:41, and then it would appear that Silas is the person intended.

With this grace - Liberal contribution. See on 2Cor 8:1 (note).

Your ready mind - Your willingness to relieve them. But, instead of ὑμων, your, ἡμων, our, is the reading of almost all the best MSS. and all the versions. This is, doubtless, the reading.