Verses with the word reserve in the Old Testament (2 verses):

Jeremiah 3:5
Will he reserve his anger for ever? will he keep it to the end? Behold, thou hast spoken and done evil things as thou couldest.

Jeremiah 50:20
In those days, and in that time, saith the LORD, the iniquity of Israel shall be sought for, and there shall be none; and the sins of Judah, and they shall not be found: for I will pardon them whom I reserve.