It is narrated from Sayyiduna Abdullah (may Allah be pleased with him): I went out with the Messenger of Allah (peace and blessings be upon him) for his call of nature, and he (peace and blessings be upon him) said: "Bring me something with which to clean myself, and do not bring me dung."
This narration, if authentic, strengthens the narration of Abu Ishaq from Abd al-Rahman bin al-Aswad, except that Layth bin Abi Sulaym is da'if (weak).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 527