the Messenger of Allah would order paying the Zakat before going to the Salat on the day of Fitr.
Jami` at-Tirmidhi Book 7, Hadith 61
← Previous Hadith "The Messenger of Allah made Sadaqatul-Fitr of Ramadan an obligation - a Sa of dried dates or a Sa of barley - required upon every free person and slave, male and female among the Muslims."

Jami` at-Tirmidhi Book 7, Hadith 60 Next Hadith → "Al-Abbas asked the Messenger of Allah about paying his charity (Zakat) in advance before its time is due (by being in possession for a whole year), he permitted him to do that."

Jami` at-Tirmidhi Book 7, Hadith 62