We find in core Islamic texts, Muhammad allows his soldiers to rape captive women:
From Sahih Muslim, a canonical hadith collection:
Book 008, Number 3371:
Abu Sirma said to Abu Sa’id al Khadri (Allah he pleased with him): 0 Abu Sa’id, did you hear Allah’s Messenger (may peace be upon him) mentioning al-‘azl? He said: Yes, and added: We went out with Allah’s Messenger (may peace be upon him) on the expedition to the Bi’l-Mustaliq and took captive some excellent Arab women; and we desired them, for we were suffering from the absence of our wives, (but at the same time) we also desired ransom for them. So we decided to have sexual intercourse with them but by observing ‘azl (Withdrawing the male sexual organ before emission of semen to avoid-conception). But we said: We are doing an act whereas Allah’s Messenger is amongst us; why not ask him? So we asked Allah’s Messenger [Muhammad] (may peace be upon him), and he said: It does not matter if you do not do it, for every soul that is to be born up to the Day of Resurrection will be born.
Notice that Muhammad did not say, “do not rape your captive women.” He merely says it does not matter if his soldiers withdraw before ejaculation, because souls destined by Allah to be born will be born regardless.
From Sahih al-Bukhari, the most canonical hadith collection:
Volume 5, Book 59, Number 459:
Narrated Ibn Muhairiz:
I entered the Mosque and saw Abu Said Al-Khudri and sat beside him and asked him about Al-Azl (i.e. coitus interruptus). Abu Said said, “We went out with Allah’s Apostle for the Ghazwa [battle at which Muhammad was present] of Banu Al-Mustaliq and we received captives from among the Arab captives and we desired women and celibacy became hard on us and we loved to do coitus interruptus. So when we intended to do coitus interruptus, we said, ‘How can we do coitus interruptus before asking Allah’s Apostle [Muhammad] who is present among us?” We asked (him) about it and he said, ‘It is better for you not to do so, for if any soul (till the Day of Resurrection) is predestined to exist, it will exist.”
Again notice that, in answer to his soldiers’ queries Muhammad doesn’t say “You must not force your captives to have intercourse with you.” He says only that coitus interruptus, withdrawing prior to ejaculation, is pointless, because souls predestined to exist will exist regardless.
Again in Sahih al-Bukhari:
Volume 7, Book 62, Number 137:
Narrated Abu Said Al-Khudri:
We got female captives in the war booty and we used to do coitus interruptus with them. So we asked Allah’s Apostle [Muhammad] about it and he said, “Do you really do that?” repeating the question thrice, “There is no soul that is destined to exist but will come into existence, till the Day of Resurrection.”
Thus Muhammad does not forbid his men to rape their captives, but merely says that it’s better not to do coitus interruptus. His men were to keep going till coitus was complete.