Sirach 28:4

4 He sheweth no mercy to a man, which is like himself: and doth he ask forgiveness of his own sins?

Sirach 28:4 In-Context

2 Forgive thy neighbour the hurt that he hath done unto thee, so shall thy sins also be forgiven when thou prayest.
3 One man beareth hatred against another, and doth he seek pardon from the Lord?
4 He sheweth no mercy to a man, which is like himself: and doth he ask forgiveness of his own sins?
5 If he that is but flesh nourish hatred, who will intreat for pardon of his sins?
6 Remember thy end, and let enmity cease; corruption and death, and abide in the commandments.

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