Al-Muwatta Hadith 20.69

Yahya related to me from Malik that he had heard that Uthman ibn Affan would sometimes never get down from the animal he was riding on when he was doing umra, until he had returned . Malik said, ''Umra is a sunna, and we do not know of any muslim who has ever said that it is permissible not to do it." Malik said, "I do not think that anyone can do more than one umra in any one year." Malik said that someone doing umra who had sexual intercourse with his wife had to sacrifice an animal and do a second umra, which he had to begin when he had finished the one that he had spoiled. He should go into ihram at the same place where he went into ihram for the umra which he had spoiled, except if he had entered into ihram at a place further away than his miqat. This was because he only had to go into ihram from his miqat. Malik said, "Someone who entered Makka to do umra, and does tawaf of the House and say between Safa and Marwa while he is junub, or not in wudu, and afterwards has intercourse with his wife, and then remembers, should do ghusl, or wudu, and then go back and do tawaf around the House and say between Safa and Marwa and do another umra and sacrifice an animal. A woman should do the same if her husband has intercourse with her while she is in ihram. " Malik said, "As for beginning umra at at-Tanim, (it is not the only alternative). It is permissible if Allah wills for some one to leave the Haram and go into ihram if he wishes, but the best way is for him to go into ihram at the miqat which the Messenger of Allah, may Allah bless him and grant him peace, used (i.e. at-Tanim), or one which is further away."