“Great is the promise which Christ makes to His disciples, the ability to move mountains, if only we are not ambiguous in faith, that is, we do not hesitate. One might ask, ‘And if I ask for something unprofitable, and foolishly believe that God will give me this, will I indeed receive this unprofitable thing?’…how could a man who is united with God as one and not divided or separated from Him, how could that man ask for something unprofitable? So if you are undivided and inseparable from God, then you will ask for and receive things which are profitable for you

(St Theophylact in ‘Commentary on Matthew’)