عَنْ سَهْلِ بْنِ سَعْدٍ السَّاعِدِيِّ رَضِيَ اللَّهُ عَنْهُ قَالَ كُنْتُ مَعَ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ بِالْخَنْدَقِ فَأَخَذَ الْكُرْزِينَ فَحَفَرَ بِهِ فَصَادَفَ حَجَرًا فَضَحِكَ قِيلَ مَا يُضْحِكُ يَا رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ قَالَ ضَحِكْتُ مِنْ نَاسٍ يُؤْتَى بِهِمْ مِنْ قِبَلِ الْمَشْرِقِ فِي النُّكُولِ يُسَاقُونَ إِلَى الْجَنَّةِ
It is narrated from Sayyiduna Sahl bin Sa’d Sa’idi (may Allah be pleased with him), he says: I was with the Noble Prophet (peace and blessings be upon him) at the time of digging the trench. The Prophet (peace and blessings be upon him) took a pickaxe and began to dig with it. Suddenly, a rock appeared in front. At that moment, the Prophet (peace and blessings be upon him) laughed. Someone asked: O Messenger of Allah! What made you laugh? The Prophet (peace and blessings be upon him) replied: I laughed because of those people who will be brought in chains from the East and will be led towards Paradise.