Mishkat al-Masabih 3817

‘Abdallah b. ‘Amr told that a man came to God’s Messenger and asked his permission to take part in jihad. He asked him if his parents were still alive, and when he replied that they were, he told him to exert himself* on their behalf.
*The point is not so clear in English as in Arabic. Jihad, while being the word for fighting against infidels, also means to strive or to exert oneself in general. The man wished to take part in jihad, and when the Prophet (ﷺ) heard that his parents were still alive he said fa-fihima fa-jahid (exert yourself on their behalf.)
(Bukhari and Muslim.) A version has, “Return to your parents and look after them well.”