I saw the Messenger of Allah ﷺ sucking his tongue, or he said his lip, meaning Hasan bin Ali, may the blessings of Allah be upon him. Surely a tongue or two lips that the Messenger of Allah ﷺ has sucked will never be punished.
حدثنا هاشم بن القاسم حدثنا حريز عن عبد الرحمن بن أبي عوف الجرشي
رأيت رسول الله ﷺ يمص لسانه أو قال شفته يعني الحسن بن علي صلوات الله عليه وإنه لن يعذب لسان أو شفتان مصهما رسول الله ﷺ
Its chain of transmission is sahih. Jareer is Ibn Hazim, and Abdul-Rahman bin Abu Awf is trustworthy, from the senior generation of the Followers, and it is said that he encountered the Prophet ﷺ. Haythami also graded the hadith sahih, 9/177.