The Prophet ﷺ said: If anyone pays in advance he must not transfer it to someone else before he receives it.  

قَالَ رَسُولُ اللَّهِ ﷺ مَنْ أَسْلَفَ فِي شَىْءٍ فَلاَ يَصْرِفْهُ إِلَى غَيْرِهِ