Sunan Abi Dawud 2351
سنن أبي داود#2351SahihNarrated 'Umar:The Prophet (ﷺ) as saying: When the night approaches from this side and the day retreats on that side, and the sun sets - according to the version of Musaddad - he who fasts has reached the time to break it
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Muhyi Al-Din Abdul HamidSahih
Shuaib Al ArnautSahih
Zubair Ali ZaiSahih Bukhari (1954) Sahih Muslim (1100)
In-book reference: 14:39