And Allah the Exalted said (in Surah Al-Kawthar) «إنا أعطيناك الكوثر» "Indeed, We have granted you Al-Kawthar." And Abdullah bin Zaid Al-Mazini narrated that the Prophet (peace be upon him) said to the Ansar that you should remain patient until you meet me at the Hawd (Pond) of Kawthar.
Narrated `Abdullah: The Prophet said, "I am your predecessor at the Lake-Fount (Kauthar) and some men amongst you will be brought to me, and when I will try to hand them some water, they will be pulled away from me by force whereupon I will say, 'O Lord, my companions!' Then the Almighty will say, 'You do not know what they did after you left, they introduced new things into the religion after you.'"
Maulana Dawood Raz
Hadith Commentary: By "new matters" are meant the prevalent innovations (bid‘at) such as the third-day gathering (tijah), recitation of Fatiha for the deceased (fatiha), fortieth-day commemoration (chehlum), reverence for taziyah, urs celebrations, qawwali, and so on. May Allah protect us from all innovations (bid‘at). Ameen.
Source: Sahih Bukhari: Commentary by Maulana Dawood Raz, Page: 7049