The sutrah is a barrier — a wall, pillar, staff or similar — placed in front of the worshipper; the Prophet ﷺ would have a short spear (ʿanazah/ḥarbah) planted for him in open ground and pray towards it (al-Bukhārī 494, 499). He ﷺ said: "When one of you prays, let him pray facing a sutrah, and let him keep close to it" (Abū Dāwūd 698, ṣaḥīḥ). The majority hold it is a strongly emphasised sunnah, while some scholars held it obligatory because of this command; either way it should not be neglected. If someone tries to pass between you and your sutrah, repel him gently, for he ﷺ said: "When one of you prays facing something that screens him from the people and someone wants to pass in front of him, let him repel him; if he refuses, let him restrain him forcibly, for he is only a devil" (al-Bukhārī 509, Muslim 505). Passing in front of a praying person is a serious sin: "If the one who passes in front of a man who is praying knew the burden he incurs, he would stand still forty — rather than pass in front of him" (al-Bukhārī 510, Muslim 507; the narrator was unsure whether he said forty days, months or years). Passing beyond the sutrah does not harm — women and donkeys would pass beyond the Prophet's spear while he prayed (al-Bukhārī 499) — and many scholars excuse passing in the crush of Masjid al-Ḥarām and similar crowded places.
Q&A · Prayer
Do I need a sutrah in front of me when I pray, and what if someone passes in front of me?
Evidence — the daleel
Sahih al-Bukhari 509 ṢaḥīḥSahih Muslim 505 ṢaḥīḥSahih al-Bukhari 510 ṢaḥīḥSahih Muslim 507 ṢaḥīḥSahih al-Bukhari 499 ṢaḥīḥSunan Abi Dawud 698
On deen2u
Informational, not a personal fatwa. Consult a qualified scholar for rulings on your situation.