Musnad Abu Ya'la al-Mawsili 112:5

Ibrahim ibn al-Hajjaj narrated to us, Maymun ibn Najih Abu al-Hasan al-Naji narrated to us, al-Hasan narrated to us, from Anas, who said: A man came to the Messenger of Allah, may Allah bless him and grant him peace, and said: "I desire Jihad, but I am not able to do it." He said: "Does anyone of your parents remain?" He said: "My mother." He said: "Then show Allah excellence in your dutifulness to her. If you do that, then you are a pilgrim, an 'Umrah performer, and a Mujahid. So if your mother is pleased with you, then fear Allah and be dutiful to her."