How did the Prophet, may Allah bless him and grant him peace, marry Umm Al-Mu'minin Juwayriyah bint Al-Harith and Umm Al-Mu'minin Safiyyah bint Huyayy and consummate the marriage with them without them observing the waiting period (iddah)?

The Prophet, peace and blessings be upon him, married the Mother of the Believers, Juwayriyya bint al-Harith, after she had made a contract with Thabit ibn Qays for her emancipation. The Prophet paid her emancipation fee and married her. Her marriage was a reason for the freeing of one hundred households from Banu al-Mustaliq from captivity. As for her istibra' (ensuring no pregnancy), it was not explicitly mentioned in the story that she underwent it, but it is necessary, as the Prophet, peace and blessings be upon him, had Safiyya bint Huyayy undergo istibra' before marrying her. This is the guidance of the Prophet, peace and blessings be upon him, and his Sunnah regarding female captives.