It is narrated from Hazrat Hudhaifah (may Allah be pleased with him) that when the Noble Prophet (peace and blessings be upon him) prayed for someone, the effects of that supplication would reach him, his children, and even his grandchildren.
Hadith Referenceمسند احمد / مسند الأنصار رضي الله عنهم / 23394
Hadith Gradingحکم دارالسلام:إسناده ضعيف لجهالة حال أبى بكر بن عمرو