Sahih Ibn Khuzaymah

Sayyiduna Abu Hurairah رضي الله عنه narrates from the Noble Prophet صلى الله عليه وسلم that he صلى الله عليه وسلم said: "Something equal to the back stick of a camel saddle is sufficient as a sutrah, even if it is as thin as a hair." Imam Abu Bakr رحمه الله says that I fear Muhammad bin Qasim made a mistake in narrating this as a marfu' (attributed to the Prophet). Imam Abu Bakr رحمه الله says that from the ahadith of the Noble Prophet صلى الله عليه وسلم, there is strong evidence that he صلى الله عليه وسلم intended the length of the back stick of a camel saddle (for the sutrah), not its width. Among these narrations of the Noble Prophet صلى الله عليه وسلم is that a spear would be planted for him صلى الله عليه وسلم and he صلى الله عليه وسلم would use it as a sutrah while praying, and the width of a spear is not like the width of the back stick of a camel saddle.

Sayyiduna Anas bin Malik (may Allah be pleased with him) narrates that I saw the Messenger of Allah (peace and blessings of Allah be upon him) performing prayer in the Eid ground, taking a spear as a sutrah. Imam Abu Bakr (may Allah have mercy on him) says that from the command of the Prophet (peace and blessings of Allah be upon him) to use an arrow as a sutrah in prayer, it becomes clear and established that in the command to use the rear wooden part of a saddle as a sutrah, what the Prophet (peace and blessings of Allah be upon him) meant was its length, not both its length and width.

Hazrat Abdul Malik bin Abdul Aziz narrates from his father, and he from his grandfather, that the Messenger of Allah (peace be upon him) said: "Make a sutrah in your prayers, even if it is with an arrow."