Question: The supplication”The Thirst has gone, the arteries are moist…” and “Oh Allah I fasted for you, I believe in you, and with your provision I break my fast“. When are they said: after breaking the fast or when breaking the fast?
Answer: “When breaking the fast. When you break your fast, you mention it. The authentic Hadith is the first one. As for the second one, it is not established”
[Sharh Saheeh al-Bukhari no. 181 side B]
He was also asked:
Question: The Hadith: Thirst has gone, the arteries are moist, and the reward is sure, if Allah wills. Is this report specifically for the one who is in the condition of summer or can it be said by the one who fasts and does not find the drying of the veins nor thirst?
Answer: “That which is apparent is that it is said in general because thirst is present when fasting, but it varies. This dhikr is said before breaking the fast or after. The affair in this is spacious“.
[Sharh Sunan Abi Dawood no. 272]
Faisal Ibn Abdul Qaadir Ibn Hassan