It was narrated from Musa bin Talhah that his father said:“We used to perform prayer while the beasts were passing in front of us. That was mentioned to the Messenger of Allah (ﷺ) and he said: ‘If something like the hand of a saddle* is placed in front of anyone of you, it will not matter whoever passes in front of him.”* It is the piece of wood on the camel saddle which is held on to (to climb onto the camel).
حَدَّثَنَا مُحَمَّدُ بْنُ عَبْدِ اللَّهِ بْنِ نُمَيْرٍ، حَدَّثَنَا عُمَرُ بْنُ عُبَيْدٍ، عَنْ سِمَاكِ بْنِ حَرْبٍ، عَنْ مُوسَى بْنِ طَلْحَةَ، عَنْ أَبِيهِ، قَالَ كُنَّا نُصَلِّي وَالدَّوَابُّ تَمُرُّ بَيْنَ أَيْدِينَا فَذُكِرَ ذَلِكَ لِرَسُولِ اللَّهِ ـ صلى الله عليه وسلم ـ فَقَالَ " مِثْلُ مُؤْخِرَةِ الرَّحْلِ تَكُونُ بَيْنَ يَدَىْ أَحَدِكُمْ فَلاَ يَضُرُّهُ مَنْ مَرَّ بَيْنَ يَدَيْهِ " .
IbnMaja
Establishing the Prayer and the Sunnah Regarding Them • Hadith 940