Amr bin Shu'ayb (may Allah have mercy on him) narrates from his father, from his grandfather (Sayyiduna Abdullah bin Amr, may Allah be pleased with them both), that the Messenger of Allah (peace and blessings be upon him) said: "There is no harm for any of you, when he gives a voluntary charity, to give it on behalf of his parents; thus its reward will reach both of them, and nothing will be reduced from his own reward."
Imam al-Tabarani (may Allah have mercy on him) said: "Only Kharijah bin Mus'ab (may Allah have mercy on him) narrated this hadith from Uthman bin Sa'd (may Allah have mercy on him)."
Hadith Referenceالمعجم الأوسط / باب الميم / 7726
Hadith Gradingمحدثین:إسناده ضعيف لضعف خارجة بن مصعب
Hadith Takhrij«قال الهيثمي: فيه خارجة بن مصعب الضبي وهو ضعيف «مجمع الزوائد ومنبع الفوائد، ج 3، ص 139»» «أخرجه الطبراني فى «الأوسط» برقم: 6950»