Sayyiduna Qays bin Sa'd (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) ordered us to fast the day of Ashura; this was before Ramadan was revealed. Then when Ramadan was revealed, he neither ordered us to fast it nor forbade us from it, and we still kept fasting it. And he had ordered us to give Sadaqat al-Fitr; then when zakah was revealed, he neither ordered us to give it nor forbade us from it, and we still kept giving it.
Hadith Referenceالمعجم الكبير للطبراني / باب القاف / 15978