10 “Or will God forget to be merciful?”. In you, from you unto another there is no mercy unless God bestow it on you: and shall God Himself forget mercy? The stream runs: shall the spring itself be dried up? “Or shall God forget to be merciful: or shall He keep back in anger His mercies?” That is, shall He be so angry, as that He will not have mercy? He will more easily keep back anger than mercy.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)