Where should the Imam stand when he prays over the body? Sunan Ibn Majah 1494

Arabic hadith text
حَدَّثَنَا نَصْرُ بْنُ عَلِيٍّ الْجَهْضَمِيُّ، حَدَّثَنَا سَعِيدُ بْنُ عَامِرٍ، عَنْ هَمَّامٍ، عَنْ أَبِي غَالِبٍ، قَالَرَأَيْتُ أَنَسَ بْنَ مَالِكٍ صَلَّى عَلَى جِنَازَةِ رَجُلٍ فَقَامَ حِيَالَ رَأْسِهِ فَجِيءَ بِجِنَازَةٍ أُخْرَى بِامْرَأَةٍ فَقَالُوا يَا أَبَا حَمْزَةَ صَلِّ عَلَيْهَا ‏.‏ فَقَامَ حِيَالَ وَسَطِ السَّرِيرِ فَقَالَ لَهُ الْعَلاَءُ بْنُ زِيَادٍ يَا أَبَا حَمْزَةَ هَكَذَا رَأَيْتَ رَسُولَ اللَّهِ ـ صلى الله عليه وسلم ـ قَامَ مِنَ الْجِنَازَةِ مُقَامَكَ مِنَ الرَّجُلِ وَقَامَ مِنَ الْمَرْأَةِ مُقَامَكَ مِنَ الْمَرْأَةِ قَالَ نَعَمْ ‏.‏ فَأَقْبَلَ عَلَيْنَا فَقَالَ احْفَظُوا
Translation
It wasnarrated that Abu Ghalib said

“I saw Anas bin Malik offeringthefuneral prayer for a man, and he stood level with his head. Thenanother funeral was brought, that of a woman, and they said: ‘O AbuHamzah! Offer the funeral prayer for her.’ So he stood level withthemiddle of the bed (the body was upon). ‘Ala’ bin Ziyad saidto him: ‘OAbu Hamzah! Is this how you saw the Messenger of Allah(ﷺ) standingin relation to the body of a man and a woman as youhave stood?’ Hesaid: ‘Yes.’ Then he turned to us and said:‘Remember this.’”