Abi Baseer from Abi Abdullah as that he said:
“Ibrahim’s father was the court astrologer of Nimrod, the son of Canaan and Nimrod did not take any step without seeking his counsel. One night Azar was studying the position of the stars and the next morning he told Nimrod, ‘I saw a strange thing last night.’ ‘What?’ asked Nimrod. He replied: ‘I saw that a boy is to take birth in our country and that he would destroy us all, and only a short time is left before his mother conceives him.’ Nimrod was amazed and asked if his conception has already taken place. Azar said: Not as yet. Though he had learnt that the same boy was going to be burnt in fire he didn’t know that he would be saved by the Almighty. Nimrod issued a diktat that women must be separated from men. Thus except for one no woman remained in the city. All were externed so that their men may not interact with them. Ibrahim’s father slept with his wife and this resulted in the conception of Ibrahim (a.s.). His father suspected the conception and he called for an experienced women to examine if his wife was pregnant. They were so expert that if a woman was pregnant they definitely knew it. So they carefully examined Ibrahim’s mother who was pregnant, but Allah, the Mighty and Sublime transferred whatever there was in her womb to her back. The midwives said: We don’t see any pregnancy. When Ibrahim (a.s.) was born his father decided to take him to Nimrod, but his wife restrained him saying that the king would kill her son. ‘Leave him to me. I shall take him to a cave and abandon him there. He will soon perish and thus you won’t be an accomplice in the murder of your son.’ The father agreed and Ibrahim’s mother took him to a cave. After suckling him she left him inside and closed the mouth of the cave with a boulder. The Almighty Allah caused his sustenance to flow from his thumb. He sucked his thumb and consumed the milk that flew from it. He grew up faster than ordinary children. His growth in a day was equal to a week’s growth in other children. In a week he grew as much as other’s grow in a month. And in a month his body developed as much as much as it develops in a year. After some days his mother took leave of Azar and came to the cave. She saw that Ibrahim (a.s.) was alive and his eyes shone like brilliant lamps. She embraced him and gave him suck. When she returned, the father asked her about Ibrahim (a.s.). She said that it has died. ‘I have buried him,’ she wept. Now whenever she got a chance she used to come to the cave and suckle Ibrahim (a.s.). This continued for quite some time. When Ibrahim (a.s.) was able to crawl on his knees and his mother had come to feed him, he clung to her and pleaded her to take him with her. ‘Have patience!’ said the mother. ‘Let me take your father’s permission.’
Thus Prophet Ibrahim (a.s.) kept his being in hiding and concealed his matter till the time he emerged and announced the command of Allah and the Almighty Allah expressed his power through him. Reference : Kamaluddin wa Tamamun Nemah Vol 1