St. Demetrius of Rostov
For he that wavereth is like a wave of the sea driven with the wind and tossed. For let not that man think that he shall receive any thing of the Lord. Because all in this life is not forever and you should rather seek for the eternal things. What do I mean by eternal? Salvation. You are living in world as a ship on the sea and you are sinking as Peter did. This is why, you should cry together with him “My Lord, save me!” And our Lord will give you His hand as he did to Peter.