She was first married in 3 Hijra to Zaid bin Hartha (RA), the freed slave of the Holy Prophet (pbuh). By this marriage the old age tradition "Not giving the daughter in marriage to the slave" was discarded and the theory of "Equality" in Islam was established.he marriage was not success and it was difficult to manage day to day affairs. Zaid bin Hartha (RA) ultimately made up his minor divorce to Zainab bint Jahash (RA). The Prophet (pbuh) persuaded him to fear Allah (S.T.) and restrain himself the extreme step of divorce had to take place Allah (S.T.) send down Angel Jibrael and informed the Holy Prophet (pbuh) to marry Zainab (RA) bint Jahash. The Holy Prophet (pbuh), by taking the existing problem (of not marrying the widow of the adopted sons) into consideration and was much worried as to how the people would feel if he (pbuh) marries with Zainab (RA).In the meantime Allah (S.T.) revealed as Allah (S.T.) had decided to give her hand in the marriage with the Holy Prophet (pbuh) by revealing the following verse as:As narrated in Muslim by Anas bin Malik (RA) the Holy Prophet (pbuh) sent the proposal to Zainab (RA) after the waiting period was completed through Zaid bin Hartha (RA). She said she could not immediately any reply and that she would consult Allah (S.T.) i.e. "Istekhara Salat". She did not even complete her prayer that Allah (S.T.) revealed the verse that her marriage was arranged up in the skies by the Lord. Zainab (RA) bint Jahash was very much pleased and she gave off all her jewellery to the slave girl. Thus he entered the category of Ummul-Mumineen.
Zainab's (RA) marriage had certain special features which distinguish her from other wives of the Prophet (pbuh). Her 'Nikah' was performed by Allah (S.T.). There were no formal gaurdian and the witnesses but the verses of Holy Quran serve this purpose. There was no dowry for this marriage as it was conducted by the command of Allah (S.T.), Allah (S.T.) stood guarantee on behalf of the Prophet (pbuh).
The old age tradition of not to marrying the wives of the adopted sons was discarded and it was declared that the adopted sons can not be considered as real ones and the widows of them one within the permisible limits of marriage. They should be called by their fathers name, they are "Brothers in Faith". Further Allah (S.T.) guaranteed security of privacy to the Prophet's household in these words as