Sayyiduna Anas bin Malik (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "Whoever uses his tongue for the truth, so that the truth is acted upon after him, his reward continues until the Day of Resurrection, then on the Day of Resurrection Allah Almighty will give him his full reward."
Ahmad recorded it; its chain contains Ubaydullah bin Abdullah bin Mawhab, about whom Ahmad said: He is not known (or: he could not be identified). (Al-Haythami says:) I say: Ibn Mawhab's teacher is Malik bin Halik bin Harithah al-Ansari, and I have not seen anyone who has written his biography.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب العلم / 767
Hadith Gradingمحدثین:إسنادہ ضعیف
Hadith Takhrij«اخرجه الامام احمد فى مسنده 266/3 اورده المؤلف فى زوائد المسند 181 ، أخرجه مسند أحمد برقم: 13392»