I've just came across a comment from a (probably Christian)
I recently stumbled upon a Hadith that said this too!
Musnad Ahmad 16245—[Mua’wiya said]: I saw the prophet sucking on the tongue or the lips of Al-Hassan son of Ali, may the prayers of Allah be upon him. For no tongue or lips that the prophet sucked on will be tormented (by hell fire)
Which I can't even believe. This is disgusting and I do believe this is not real. So I searched for a while. What I came across is
ولن يعذب لسان او شفتان مصهما رسول الله صلى الله عليه وسلم
Referenced from musnad imam ahmad. v: 4. p: 91 — kanz-ul haqaiq. p: 62
And made a few more search and found the following Arabic websites discussing this issue
However, I have no Arabic background to understand them. Can anyone shed some light about this issue?