Short answer
The authentic dua Dhahaba al-zama'u wabtallatil-'uruq is said after you have broken the fast, since it means the thirst has gone. Start with Bismillah, eat a date or drink water, then say it. The other well-known dua, Allahumma laka sumtu, comes in a weaker report and is said at the moment of iftar. Any dua before iftar is good too.
It is sunnah to hasten iftar at sunset, beginning with Bismillah. The dhikr reported from the Prophet ﷺ is said on breaking the fast. No dua is a condition of the fast, and the time just before iftar is a good time to ask Allah.
The four schools agree on this.
Explanation
Ibn Umar reported that when the Prophet ﷺ broke his fast he would say: Dhahaba al-zama'u wabtallatil-'uruqu wa thabatal-ajru in sha Allah, meaning: the thirst has gone, the veins are moistened, and the reward is certain if Allah wills. Its wording describes what has just happened, so it is said after the first sip or date.
A simple order:
- Make your own dua in the minutes before sunset.
- At sunset, say Bismillah and break the fast at once with a date or water.
- Then say Dhahaba al-zama'u...
- Pray Maghrib, then eat your meal. See iftar and Maghrib.
Allahumma laka sumtu. Many people say Allahumma laka sumtu wa 'ala rizqika aftartu (O Allah, for You I fasted and with Your provision I break my fast). Abu Dawud records it from Mu'adh ibn Zuhrah without a Companion's name, so its chain is weak. Scholars allow it as a dua of virtue, since its meaning is sound, and many say it at the moment of breaking the fast. You may say both.
Do not delay iftar to finish a long dua: the Prophet ﷺ said people remain upon good as long as they hasten the iftar. For the Arabic, transliteration and meaning, see dua for breaking the fast, and for the dua at the start of the fast see dua for starting the fast.
The evidence
Quran, Surah Al-Baqara 2:186
وَإِذَا سَأَلَكَ عِبَادِى عَنِّى فَإِنِّى قَرِيبٌ ۖ أُجِيبُ دَعْوَةَ ٱلدَّاعِ إِذَا دَعَانِ ۖ فَلْيَسْتَجِيبُوا۟ لِى وَلْيُؤْمِنُوا۟ بِى لَعَلَّهُمْ يَرْشُدُونَ ﴿١٨٦﴾
And when My servants ask you, [O Muhammad], concerning Me - indeed I am near. I respond to the invocation of the supplicant when he calls upon Me. So let them respond to Me [by obedience] and believe in Me that they may be [rightly] guided.
This promise comes in the middle of the verses on fasting, so the fasting person's dua is especially hoped for.
Sunan Abi Dawud 2357
Grading to be checked... ذهب الظمأ وابتلت العروق وثبت الأجر إن شاء الله ...
"The thirst has gone, the veins are moistened, and the reward is certain if Allah wills."
The authentic words said on breaking the fast.
Sahih al-Bukhari 1957
Sahih... لا يزال الناس بخير ما عجلوا الفطر ...
"People will remain upon good as long as they hasten to break the fast."
Iftar is not delayed for the sake of a dua.
Where the ruling is recorded
- Nur al-Idah with Maraqi al-Falah, Kitab al-Sawm, section on what is recommended for the fasting person. Hastening iftar and saying the reported dua are recommended.
Checked by our team. For a more accurate answer to your own situation, consult a scholar. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.