Sunan Abi Dawud 4646
سنن أبي داود#4646SahihNarrated Safinah: The Prophet (ﷺ) said: The Caliphate of Prophecy will last thirty years; then Allah will give the Kingdom of His Kingdom to anyone He wills. Sa'id told that Safinah said to him: Calculate Abu Bakr's caliphate as two years, 'Umar's as ten, 'Uthman's as twelve and 'Ali so and so. Sa'id said: I said to Safinah: They conceive that 'Ali was not a caliph. He replied: The buttocks of Marwan told a lie
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniHasan Sahih
Muhammad Muhyi Al-Din Abdul HamidHasan Sahih
Zubair Ali ZaiIsnaad Hasan
In-book reference: 42:51