Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) transmits this statement of the Prophet (peace and blessings be upon him): "Hearts are vessels, and some of them retain better than others. O people, when you ask of Allah Almighty, ask Him while you are certain of being answered, for Allah Almighty does not answer the supplication of a servant who supplicates with a heedless heart."
Ahmad recorded it, and its chain is hasan (good).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الأدعية / 17203
Hadith Gradingمحدثین:إسنادہ حسن۔
Hadith Takhrij«اخرجه احمد فى المسند (6655) ، أخرجه مسند أحمد برقم: 6617»