Jamieson, Fausset and Brown on 2 Corinthians 8:2

2. trial of affliction--The Greek expresses, "in affliction (or, 'tribulation') which tested them"; literally, "in a great testing of affliction."

abundance of their joy--The greater was the depth of their poverty, the greater was the abundance of their joy. A delightful contrast in terms, and triumph, in fact, of spirit over flesh.

their deep poverty--Greek, "their poverty down to the death of it."

abounded unto the riches of their liberality--another beautiful contrast in terms: their poverty had the effect, not of producing stinted gifts, but of "abounding in the riches of liberality" (not as Margin, "simplicity"; though the idea of singleness of motive to God's glory and man's good, probably enters into the idea); (compare Ro 12:8, and Margin; 2Co 9:11, Margin; see on 2Co 9:13; Jas 1:5).