Gabriel said to him (S)...
Gabriel said to him (S): "O Muhammad, your Lord commands you to break your fasting with this food tonight." Imam ‘Ali Ibn Abu Talib (as) said in this regard: "The Prophet (S) used to order me to open the door to whoever wanted to join him when he came to break his fast, but that night he ordered me to guard the door of the house, and said to me: `O son of Abu Talib! this food is forbidden to everyone save me.
" Then he (‘Ali) (as) said: "I sat at the door, and the Prophet (S) uncovered the plate, in privacy, to find a cluster of dates and a bunch of grapes; he ate until satisfied, and drank his need of water. He then extended his hands to be washed, so Gabriel poured the water, Michael washed his hands, and Israfil dried them. Thereafter, the remaining food with the plate ascended to heaven.
Then he (as) started to prepare himself for prayers when Gabriel said to him: "Prayer is forbidden to you until you go to Khadija's house, and perform coition with her; for Allah (Glory be to Him) ordained upon Himself to create noble progeny from you tonight.' So, he rushed to Khadija's house." Khadija said: "I had gotten used to seclusion by that time, so when night arrived I covered my head, put down the curtains, locked the doors, performed my prayers, put out the lantern, and retired to my bed.
That night while I was between the states of sleeping, and being awake, the Prophet knocked on the door; so I exclaimed: Who is knocking on the door that only Muhammad knocks on?" The Prophet gently and politely replied: "Open the door Khadija, I am Muhammad" Khadija said: "I cheerfully got up, and opened the door for the Prophet to come in. He (as) usually requested the water jug to perform ablution, and two short prayer prostrations before he retired.
On the contrary, that night he (as) did not request the jug, nor, did he perform prayers... instead, what occurs between a woman and her husband occurred between us; and by Allah, who created the heavens, and caused water to come out of springs, before the Prophet left me, I felt Fatima's weight in my womb..." It can be concluded from the above mentioned narration that: Allah Almighty commanded His Messenger to abandon Khadija a period of time so that his longing, and wanting her increased.
The Prophet (S) performed more worship so as to achieve a higher level of spirituality, and sacredness, as a result of being in constant contact with the heavenly world.