Hadith 981:13
Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from 'Asim, who said: I said to Abu al-'Aliyah: "Who is Thawban?" He said: "The freed slave of the Messenger of Allah, may Allah bless him and grant him peace." He said: The Messenger of Allah, may Allah bless him and grant him peace, said: "Whoever guarantees for me that he will not ask people for anything, I will guarantee Paradise for him." Thawban said: "I [will]." And he would not ask anyone for anything.
حدثنا محمد بن جعفر، حدثنا شعبة، عن عاصم قال: قلت لأبي العالية: ما ثوبان؟ قال: مولى رسول الله صلى الله عليه وسلم قال: قال رسول الله صلى الله عليه وسلم: " من يتكفل لي أن لا يسأل شيئا وأتكفل له بالجنة؟ " فقال ثوبان: أنا فكان لا يسأل أحدا شيئا