Sand turns into Flour

 Imam Ja‘far as-Sadiq says:
Ibrahim was the first person for whom the desert sand turned into flour. It was when he had gone to Egypt to one of his friends to borrow some food grains, but did not find him home. Ibrahim did not like that he should take back his beasts of burden empty. So he filled the sacks with sand. When he reached home, he sent the loaded animals inside to Sarah and he went to sleep in a secluded place. Sarah opened the sacks to find the best quality flour. She prepared leavened breads and carried them to Ibrahim.
“Where did you get there breads from?” asked Ibrahim.
“They are prepared from the same flour that you brought from your Egyptian friend.”
“Indeed one who gave me this flour is my friend but not that Egyptian friend (Khalil),” said Ibrahim. It was for this reason that Allah appointed him as His Khalil.
Thus Ibrahim thanked the Almighty and consumed his food.

Another tradition says that Ibrahim was very particular in entertaining guests. One day some guests arrived while he had nothing to offer them. Ibrahim thought that if he sold some wood to the wood cutter he would carve idols from it so that was out of question. Meanwhile he housed the guests in the guest room. Then taking a bag with him he went to the desert and prayed two Rak’ahs (units) prayers. After the prayers he found the bag missing. Upon his return he found Sarah cooking something. He asked her as to how she had obtained the ingredients. She said they were the same that a person delivered on his directions. Actually the Almighty had ordered Archangel Gabriel to pick up the bag where Ibrahim had prayed and to fill it with sand and stones. Then He converted the sand into clean Bajra flour, the round stones into beetroot and the elongated stones into carrots.

Reference: Hayat Al-Qulub, Vol. 1, Stories of the Prophets