Abstain means to withhold oneself from an action or self-indulgence.

• There were six votes in favour, two against and two abstaining ; He abstained from drinking.

Refrain has to do with withholding an action temporarily, or checking a momentary desire: She refrained from scolding her child until the company left. To forbear , in its intransitive sense, is to exercise self-control, often out of motives of patience or charity.

• Though impatient, the customer forbore to upbraid the harried salesgirl; The teacher forbore to report Johnnie’s misbehaviour to his parents.