Sayyiduna Abu Umamah al-Bahili (may Allah be pleased with him) narrates this saying of the Prophet (peace and blessings be upon him): "There are four kinds of people whose rewards continue even after death: a man who is standing guard in the path of Allah; a person who does a deed such that he is rewarded with the like of whoever does as he did; a person who gives something in charity, whose deed continues for as long as that charity remains in use; and a person who leaves behind a righteous child who prays for him."
Imam Ahmad recorded this narration. One chain of it has already passed before this, in the chapter concerning acquiring knowledge. Its chain contains a narrator, Ibn Lahi'ah, and he has been criticised.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الزكاة / 4758
Hadith Gradingمحدثین:إسناده ضعیف
Hadith Takhrij«اخرجه الطبراني فى المعجم الكبير (261/5) ، أخرجه مسند أحمد برقم: 21744»