Thomas Boston, Works, 3:299:
Repenting under a rod is profitable, but repining is hurtful. Suppose repentance have a bitterness with it, yet since we must be in bitterness, better repent than repine. If we feel the prickles of the rose bush, yet there is something pleasant and profitable to be gathered of it. But to be scratched with briers, the scratching is all; there is nothing worth the pains growing upon them. Repentance has joy included in it, but repining all over has nothing desirable.
Source: http://www.puritanboard.com/f25/better-repent-than-repine-83808/, Comment #1 (Thank You, Reverend Winzer!)