Sirach 38:21

21 Forget it not, for there is no turning again: thou shalt not do him good, but hurt thyself.

Sirach 38:21 In-Context

19 In affliction also sorrow remaineth: and the life of the poor is the curse of the heart.
20 Take no heaviness to heart: drive it away, and member the last end.
21 Forget it not, for there is no turning again: thou shalt not do him good, but hurt thyself.
22 Remember my judgment: for thine also shall be so; yesterday for me, and to day for thee.
23 When the dead is at rest, let his remembrance rest; and be comforted for him, when his Spirit is departed from him.

The Brenton translation of the Septuagint is in the public domain.