The Prophet ﷺ said: A beggar has the right though he may be riding (a horse).  

قَالَ رَسُولُ اللَّهِ ﷺ لِلسَّائِلِ حَقٌّ وَإِنْ جَاءَ عَلَى فَرَسٍ  

The above mentioned tradition has also been transmitted by 'Ali through a different chain of narrators in a similar manner from the Prophet ﷺ.  

عَنِ النَّبِيِّ ﷺ مِثْلَهُ  

She took the oath of allegiance to the Messenger of Allah ﷺ and said to him: Messenger of Allah, a poor man stands at my door, but I find nothing to give him. The Messenger of Allah ﷺ said to her: If you do not find anything to give him, put something in his hand, even though it should be a burnt hoof.  

عَنْ جَدَّتِهِ أُمِّ بُجَيْدٍ وَكَانَتْ مِمَّنْ بَايَعَ رَسُولَ اللَّهِ ﷺ أَنَّهَا قَالَتْ لَهُ يَا رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْكَ إِنَّ الْمِسْكِينَ لَيَقُومُ عَلَى بَابِي فَمَا أَجِدُ لَهُ شَيْئًا أُعْطِيهِ إِيَّاهُ فَقَالَ لَهَا رَسُولُ اللَّهِ ﷺ إِنْ لَمْ تَجِدِي لَهُ شَيْئًا تُعْطِينَهُ إِيَّاهُ إِلاَّ ظِلْفًا مُحْرَقًا فَادْفَعِيهِ إِلَيْهِ فِي يَدِهِ