It was narrated that Abu Hurairah said:"None of you should urinate into standing water which does not flow and then perform Ghusl with it." (One of the narrators) Sufyan said: "They said to Hisham - meaning Ibn Hassan - 'Ayyub only attributed this Hadith to Abu Hurairah?' So he said: 'If Ayyub is not able to raise up a narration then he does not raise it.'" [1] [1] That is, he narrated it from Abu Hurairah, rather than from him from the Prophet (ﷺ) while others narrated it in Marfu' form or "raised" to the Prophet (ﷺ) And perhaps by: "If he is able to not raise it" he means: "If he is not able to raise it." And Allah knows best.
أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا سُفْيَانُ، عَنْ أَيُّوبَ، عَنِ ابْنِ سِيرِينَ، عَنْ أَبِي هُرَيْرَةَ، قَالَ لاَ يَبُولَنَّ أَحَدُكُمْ فِي الْمَاءِ الدَّائِمِ الَّذِي لاَ يَجْرِي ثُمَّ يَغْتَسِلُ مِنْهُ . قَالَ سُفْيَانُ قَالُوا لِهِشَامٍ - يَعْنِي ابْنَ حَسَّانَ - أَنَّ أَيُّوبَ إِنَّمَا يَنْتَهِي بِهَذَا الْحَدِيثِ إِلَى أَبِي هُرَيْرَةَ فَقَالَ إِنَّ أَيُّوبَ لَوِ اسْتَطَاعَ أَنْ لاَ يَرْفَعَ حَدِيثًا لَمْ يَرْفَعْهُ .
Nesai
The Book of Ghusl and Tayammum • Hadith 400