[Ruling on Coitus Interruptus and the Use of Contraceptive Treatment]

The answer—and Allah is the One who grants success: The apparent ruling is that this is permissible, for the evidences that came in the Qurʾān prohibited the killing of children and the burying of newborn girls alive; and a sperm-drop is not called a “child,” nor is its spoiling called “killing.”
This is indicated by His—Exalted is He—saying: "And indeed We created man from an extract of clay. Then We placed him as a sperm-drop in a firm lodging. Then We developed the sperm-drop into a clinging clot, then We developed the clot into a lump [of flesh], then We developed the lump into bones, and We covered the bones with flesh; then We produced him as another creation. So blessed is Allah, the best of creators." [Al-Muʾminūn:12–14].
If the spirit has not yet been breathed into it, then spoiling it is permissible and is not called “killing”—this being while it is a sperm-drop, a clinging clot, or a lump of flesh.
Killing is the taking of the soul of one who possesses a soul, and in what we have mentioned there is no soul. In the ḥadīth: that the Prophet (May Allah bless him and his family and grant them peace) forbade coitus interruptus with a free woman except with her permission. This is the conclusion in al-Shifāʾ and Uṣūl al-Aḥkām.
And in Uṣūl al-Aḥkām: that the Messenger of Allah (May Allah bless him and his family and grant them peace) permitted coitus interruptus.
On this subject there are many ḥadīths, mentioned in Tatimmat al-Iʿtiṣām.
And it is mentioned in a narration from ʿAlī (peace be upon him) about coitus interruptus: “It is hidden infanticide; so do not approach that.” This is mentioned in the Amālī of Aḥmad ibn ʿĪsā.
And another narration from the Prophet (May Allah bless him and his family and grant them peace), reported by the Six except al-Bukhārī, in which they said: they asked the Prophet (May Allah bless him and his family and grant them peace) about coitus interruptus, and he (May Allah bless him and his family and grant them peace) said: “That is hidden infanticide.”
The author of the Tatimmah said: I say—and with Allah is success—these reports, some prohibiting and some permitting—when in apparent contradiction—are carried upon dislike (karāhah) as a reconciliation between them; and Allah knows best.
Source : Min Thimār al-ʿIlm wa al-Ḥikmah vol.1