Does the master need the consent of his female slave to do azl? With the fatwa, seerah, and Hadith
Consent of a concubine is not necessary for practising 'azl (coitus interruptus) with her.
The evidence is the hadith:
أن رجلا، أتى رسول الله صلى الله عليه وسلم فقال إن لي جارية هي خادمنا وسانيتنا وأنا أطوف عليها وأنا أكره أن تحمل . فقال " اعزل عنها إن شئت فإنه سيأتيها ما قدر لها
A man came to Allah's Messenger (ﷺ) and said: I have a slave-girl who is our servant and she carries water for us and I have intercourse with her, but I do not want her to conceive.
He said: Practise 'azl, if you so like, but what is decreed for her will come to her.
This hadith permits 'azl with a concubine, and does not put a condition of consent. If consent was necessary then the Prophet ﷺ would have inquired about this and informed the person to seek her permission first. Similarly the other ahadith on practicing 'azl with concubines do not mention getting their permission.
The traditions that mention the condition of consent are limited to a free woman:
نهى رسول الله ـ صلى الله عليه وسلم ـ أن يعزل عن الحرة إلا بإذنها
The Messenger of Allah forbade practicing coitus interruptus with a free woman except with her consent.
It is also evident from reasoning. Unlike a wife, a concubine does not have a right to division of nights, or to intercourse at all (Quran 4:3) and 'azl is a form of incomplete intercourse. When she is not entitled to intercourse at all then it is even more appropriate that she is not entitled to a completion or perfection of the act.
There is Ijma' on this, as claimed by various scholars such as:
ويجوز عن السرية بغير إذنها إجماعا
It is permissible with a concubine without her consent, by consensus
With the exception of some minority madhabs who consider 'azl to be categorically haram. In this case they would forbid it regardless of whether the concubine consents.
The Hanafis, Malikis, Shafi'is and Hanbalis agrees with this.
ويجوز العزل عن أمته بغير إذنها نص عليه أحمد. وهو قول مالك، وأبي حنيفة، والشافعي
It is permissible to perform 'azl with a concubine without her permission. This has been stated by Ahmad (ibn Hanbal) and is also the saying of Malik, Abu Hanifa and Shafi'i