Wa `alaykum As-Salamu waRahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
1- The wife’s right to have a baby is firmly established in Islamic Law. The husband is by no means entitled to deny her this inalienable right.
2- It is, accordingly, incumbent upon both of them to reach mutual agreement regarding the practice of coitus interruptus or using contraceptives, otherwise, the husband will be sinful from the Islamic point of view and have committed an act contradicting the Shari`ah objectives.
Answering your question, Dr. Husam al-Din Ibn Musa `Afana, Professor of Principles of Islamic Jurisprudence at Al-Quds University, Palestine, states:
Scholars have agreed that the wife is fairly entitled to give birth to a baby. If her husband uses contraceptives such as coitus interruptus and other new means of contraception, he definitely harms his wife.
It is, in effect, well-known that Islam prohibits doing harm to the wife and others. Therefore, the majority of scholars have permitted the practice of coitus interruptus provided that it’s done with mutual agreement between the husband and his wife.
By analogy, the same ruling is applicable with respect to modern means of contraception used by the husband to prevent pregnancy.
Sheikh Ibn Qudamah al-Maqdsi said: “A husband should not practice coitus interruptus with his wife unless he takes her permission. Abu Ya`la, the Judge, stated that the apparent words of Imam Ahmad is that taking the wife’s permission is a must. This is based on the Hadith reported by Ahmad and Ibn Majah quoting `Umar as saying: “The Messenger of Allah (peace be upon him) has prohibited a husband to practice coitus interruptus unless it is done at the consent of the wife.”
This is because she has the right to give birth to a baby and will be harmed by coitus interruptus; so, it is only permissible with her consent.” (Al-Mughni, 7: 298)
Al-Buhuti, the Hanbali scholar also stated that it is not permissible for the husband to practice coitus interruptus without the permission of his wife. (Kashf al-Qina`, 3: 112)
Ibn Hajar said: “The three schools of Islamic jurisprudence, have unanimously agreed that one should seek his wife’s permission before practicing coitus interruptus.” By the three schools he meant the Hanafi, Maliki, and Hanabli schools. The Shafi`i school, however, hold two opinions, one of which is in line with the three schools’ view.
Ibn Hajar further adds: “The Salaf (first generation of Muslims) hold different opinions concerning the practice of coitus interruptus. According to Ibn `Abd al-Barr, scholars have unanimously agreed that the wife’s permission is a must before practicing coitus interruptus.
The reason behind this is that the wife has right to enjoy and demand sexual intercourse, which is known to be interrupted by coitus interruptus. The consensus of the scholars on this issue is also reported by Ibn Hubayrah.” (Fat-h al-Bari, 3: 382)
Almighty Allah knows best.