Sunan Abi Dawud 1266
سنن أبي داود#1266SahihNarrated Abu Hurairah:The Messenger of Allah (ﷺ)as saying: When the iqamah is pronounced for prayer, no prayer is valid except the obligatory prayer
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 Muslim (710)
In-book reference: 5:17