The Size of the Praying Person's Sutrah

Question:
What is the size of the praying person's sutrah? And who invalidates the prayer? And if the prayer is invalidated, is it repeated or not?

Answer:
In the name of Allah, and praise is to Allah. The sutrah of the praying person is the size of the back of a saddle, as the Prophet (peace and blessings be upon him) explained, and it is approximately an arm's length minus a quarter. If there is a wall, pillar, or chair of this size or similar in front of the praying person, that suffices as a sutrah. If he does not find one, he should place something like a stick or similar, or draw a line if it is on ground where the line is visible. It is known that the sutrah is a recommended practice (sunnah) and not obligatory, based on the saying of the Prophet (peace and blessings be upon him): Narrated by Abu Dawud with a sound chain.
It is also established from him (peace and blessings be upon him) that he prayed in some places without a sutrah; this indicates that the command regarding the sutrah is for recommendation, not obligation. It is also authentic from him (peace and blessings be upon him) that he said: Muslim narrated it in his Sahih from the hadith of Abu Dharr (may Allah be pleased with him), and he narrated a similar one from the hadith of Abu Hurayrah (may Allah be pleased with him), but it does not specify the dog as black. The unrestricted is understood according to the restricted, in accordance with the established legal principle mentioned in the books of usul al-fiqh and hadith terminology.
It is also authentic from the hadith of Ibn Abbas (may Allah be pleased with him) that the woman is specified as the menstruating one, who is an adult; this indicates that a young girl does not invalidate the prayer. It is prescribed for the Muslim to turn back anyone who wants to pass in front of him, whether a person or otherwise, based on the saying of the Prophet (peace and blessings be upon him): Agreed upon as authentic.
This ruling applies to the imam and the one praying alone. As for the ma'mum, his sutrah is the sutrah of his imam, and it does not harm him if any of these three or others pass in front of him.
The Sacred Mosque is also an exception to this, as it does not harm the praying person in it if anyone passes in front of him, based on known evidence for this.
These three invalidate the prayer of the Muslim man and woman if one of them passes in front of him or in front of her within the limit of three arm's lengths from the feet of the praying person or less, if they do not have a sutrah.
If they have a sutrah, these three invalidate the prayer if one of them passes between the praying person and the sutrah, and he is obligated to repeat it if the prayer is obligatory, except in the Sacred Mosque as mentioned earlier. And success is from Allah.