A.T. Robertson Commentary 2 Corinthians 9:7

"[Let] each man [do] according as he hath purposed in his heart: not grudgingly, or of necessity: for God loveth a cheerful giver." — 2 Corinthians 9:7 (ASV)

He hath purposed (προηιρητα). Perfect middle indicative of προαιρεομα, to choose beforehand, old verb, here only in N.T. Permanent purpose also.

Not grudgingly (μη εκ λυπης). The use of μη rather than ου shows that the imperative ποιειτω (do) or διδοτω (give) is to be supplied. Not give as out of sorrow.

Or of necessity (η εξ αναγκης). As if it were like pulling eye-teeth.

For God loveth a cheerful giver (ιλαρον γαρ δοτην αγαπα ο θεος). Our word "hilarious" comes from ιλαρον which is from ιλαος (propitious), an old and common adjective, only here in N.T.