He asked the Messenger of Allah ﷺ, "Which deed is best?"He replied, "Hold fast to fasting, for nothing equals it."
أخبرني عبد الله بن محمد الضعيف شيخ صالح والضعيف لقب لكثرة عبادته قال أخبرنا يعقوب الحضرمي قال حدثنا شعبة عن محمد بن عبد الله بن أبي يعقوب عن أبي نصر عن رجاء بن حيوة
أنه سأل رسول الله ﷺ أي العمل أفضل قال عليك بالصوم فإنه لا عدل له
[Sahih] Reported by Ibn Hibban, no. 930, and Ibn Khuzayma, no. 1893, in their two Sahihs, from the hadith of Shuba by this route. It is also in Kubra, no. 2532. Hakim declared it sahih, 1/421, as did Dhahabi, who said, "Abu Nasr Hilali is Humayd bin Hilal Adawi, and its chain is only hasan." Abu Nasr is not unknown. Ibn Khuzayma, Hakim, and others confirmed his reliability, he was not alone in narrating it, and his hadith has corroborating narrations.