The Gravity of (Telling) a Lie against Allah's Messenger صلى الله عليه وسلم

بسم الله الرحمن الرحيم ( bismi-llāhi r-raḥmāni r-raḥīm ) 

In the name of  Allah, The Most Gracious, The Most Merciful

Hadith No 1.

Narrated Ali (Razi Allah tala anhu) : The Prophet صلى الله عليه وسلم said, "Do not tell a lie against me, for whoever tells a lie against me (intentionally) then he will surely enter the Hell-fire." 

(Sahîh Al-Bukhâri, Hadîth No. 106, Vol. 1)