Mishkat al-Masabih 3898
Abu Sa'id al-Khudri said:
While we were on a journey with God’s Messenger a man came on a riding beast and began to turn right and left,* whereupon God’s Messenger said, “He who has an extra mount should lend it to him who has none, and he who has extra provision should give it to him who has none.” He said that he mentioned various kinds of property till they began to think none of them had a right to anything extra. 

* The camel was evidently tired, and the man seems to have been looking around to see whether he could get any help. Another suggestion is that the man was walking with his goods loaded on the camel, but the wording hardly supports this. Cf. Mirqat , iv, 213 f.

Muslim transmitted it.
وَعَن أبي سعيد الْخُدْرِيّ قَالَ: بَيْنَمَا نَحْنُ فِي سَفَرٍ مَعَ رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ إِذ جَاءَهُ رَجُلٌ عَلَى رَاحِلَةٍ فَجَعَلَ يَضْرِبُ يَمِينًا وَشِمَالًا فَقَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «مَنْ كَانَ مَعَهُ فَضْلُ ظَهْرٌ فَلْيَعُدْ بِهِ عَلَى مَنْ لَا ظَهْرَ لَهُ وَمَنْ كَانَ لَهُ فَضْلُ زَادٍ فَلْيَعُدْ بِهِ عَلَى مَنْ لَا زَادَ لَهُ» قَالَ: فَذَكَرَ مِنْ أَصْنَافِ الْمَالِ حَتَّى رَأَيْنَا أَنَّهُ لَا حَقَّ لأحدٍ منا فِي فضل. رَوَاهُ مُسلم