What is the minimum amount of hair that must be removed (shortened) during ritual hair trimming (Taqsir)?
Chapter on Mentioning Hajj and Entering Makkah
Al-Mughni
Book of Hajj
Primary text
Any amount shortened suffices because the command for shortening is absolute and thus encompasses the minimum amount. Imam Ahmad stated that the minimum is the measure of one phalanx (one joint of a finger), which is also the view held by Ibn Umar, Al-Shafi'i, Ishaq, and Abu Thawr. This minimum quantity is understood to be for the recommendation (Istihbab), supported by the report that Ibn Umar stated that trimming with anything suffices.
Supporting text
The act of plucking or removing hair with depilatory agents also suffices because the intent is removal, and the command is absolute, covering whatever is termed 'removal'. However, the Sunnah is shaving or shortening in emulation of the Messenger of Allah, peace be upon him, and his Companions.