It is narrated from Ibn Umar (may Allah be pleased with them both) that a man passed by them, and they marvelled at his fine build. They said: If only he were in the path of Allah! They came to the Prophet (peace and blessings be upon him), and the Prophet (peace and blessings be upon him) said: "If he is serving his elderly parents, he is in the path of Allah; if he is striving for his young children, he is in the path of Allah; and if he is striving for himself to make himself self-sufficient, he is in the path of Allah."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النفقات / 15742