Ja'far bin Muhammad (may Allah have mercy on him) narrates from his father (may Allah have mercy on him) that he used to drink from the water points set up along the roads, which people had placed between Makkah and Madinah. I said to him — or it was said to him — about this, and he said: "Only the obligatory charity has been made unlawful for us."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الهبات / 12039