Fighting for the Cause of Allah (Jihaad)
حَدَّثَنَا آدَمُ، حَدَّثَنَا شُعْبَةُ، حَدَّثَنَا حَبِيبُ بْنُ أَبِي ثَابِتٍ، قَالَ سَمِعْتُ أَبَا الْعَبَّاسِ الشَّاعِرَ ـ وَكَانَ لاَ يُتَّهَمُ فِي حَدِيثِهِ ـ قَالَ سَمِعْتُ عَبْدَ اللَّهِ بْنَ عَمْرٍو ـ رضى الله عنهما ـ يَقُولُ جَاءَ رَجُلٌ إِلَى النَّبِيِّ صلى الله عليه وسلم فَاسْتَأْذَنَهُ فِي الْجِهَادِ فَقَالَ " أَحَىٌّ وَالِدَاكَ ". قَالَ نَعَمْ. قَالَ " فَفِيهِمَا فَجَاهِدْ ".Narrated `Abdullah bin `Amr:A man came to the Prophet (ﷺ) asking his permission to take part in Jihad. The Prophet (ﷺ) asked him, "Are your parents alive?" He replied in the affirmative. The Prophet (ﷺ) said to him, "Then exert yourself in their service
From Sahih al-Bukhari, whose reports the scholars accept as authentic.