Some said about abba Moses from the skete that wanting to come to Petra he got tired of walking. And he said for himself:
`How can I gather water here?`
A voice came and told him:
`Go in and do not worry at all.`
So he got in and some monks came to him and he had only a small jug with water. He boiled some lentils and the water was over. The elder got upset. So going in and out he prayed to God and a cloud came over Petra and filled all his jugs.
After that they asked him :
`Tell us why were you going in and out?`
The elder told them:
`I was talking with God because He brought me here and I don`t have water to give to his servants to drink. For this I was going in and out praying to God until He sent us rain.
Excerpt from The Egyptian Patericon – Abba Moses the Moor