Sayyiduna Abu Umamah (may Allah be pleased with him) narrates: I said: "O Messenger of Allah! Guide me to a deed (that will take me to Paradise)." He (peace and blessings be upon him) said: "Hold fast to fasting, for there is nothing equal to it." The chain of this hadith is sahih, but the two Shaykhs did not record it. Muhammad bin Abi Ya'qub is the narrator about whom Imam Shu'bah, whenever he narrated from him, would say: "The chief of Banu Tamim narrated to me." And Abu Nasr al-Hilali is in fact Humayd bin Hilal al-Adawi. I do not know of anyone who narrated it from Imam Shu'bah other than Abd al-Samad, and he is trustworthy and reliable.