The Prophet ﷺ said: If anyone seeks protection in Allah's name, grant him protection; if anyone begs in Allah's name, give him something; if anyone gives you an invitation, accept it; and if anyone does you a kindness, recompense him; but if you have not the means to do so, pray for him until you feel that you have compensated him.  

قَالَ رَسُولُ اللَّهِ ﷺ مَنِ اسْتَعَاذَ بِاللَّهِ فَأَعِيذُوهُ وَمَنْ سَأَلَ بِاللَّهِ فَأَعْطُوهُ وَمَنْ دَعَاكُمْ فَأَجِيبُوهُ وَمَنْ صَنَعَ إِلَيْكُمْ مَعْرُوفًا فَكَافِئُوهُ فَإِنْ لَمْ تَجِدُوا مَا تُكَافِئُونَهُ فَادْعُوا لَهُ حَتَّى تَرَوْا أَنَّكُمْ قَدْ كَافَأْتُمُوهُ