It is narrated from Hazrat Abu Huraira (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: There are three types of people whose supplications are accepted and there is no doubt about their acceptance: the supplication of the oppressed, the supplication of the traveler, and the supplication of a father regarding his son.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 7510
Hadith Gradingحکم دارالسلام:حسن لغيره، وإسناد الحديث كسابقه.