After this do we not feel shame, and hide our faces, at seeing that righteous man for twenty years persevering and not desisting; we ourselves after a first or second petition often fainting and indignant? And yet he indeed had in large measure liberty of speech towards God, and all the same he felt no discontent at the delay of the giving, but remained patient, whereas we—laden with countless sins, living with an evil conscience, displaying no good will towards the Master—if we are not heard before having spoken, are bewildered, impatiently recoil, desist from asking. On this account we always retire with empty hands.

Who has for twenty years besought God for one thing, as this righteous man did? Or rather who for twenty months only?

Saint John Chrysostom
On the Power of Prayer and Forgiveness
Homilies on Profitable Subjects