Jami` at-Tirmidhi 2710
جامع الترمذي#2710SahihNarrated 'Amr bin Abi Sufyan:that 'Amr bin 'Abdullah bin Safwan informed him, that Kaladah bin Hanbal had informed him, that Safwan bin Umayyah sent him to bring some milk, colostrum, and Daghabis (a type of herb) to the Prophet (ﷺ) while he was in the upper valley. (He said): "I entered upon him without seeking permission nor giving Salam. The Prophet (ﷺ) said: 'Go back and say: As-Salamu Alaykum, may I enter?'" And that was after Safwan had accepted Islam
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Ahmad Muhammad ShakirSahih
Al-AlbaniSahih
Bashar Awad MaaroufHasan
Zubair Ali ZaiIsnaad Hasan
In-book reference: 42:23