Sunan Ibn Majah, Volume 2, Book 5, Hadith 908 (DarusSalam) ⓘ
It was narrated that Ibn ‘Abbas said: “The Messenger of Allah said: ‘Whoever forgets to send peace and blessings upon me, then he has missed the road to Paradise.’”
حَدَّثَنَا جُبَارَةُ بْنُ الْمُغَلِّسِ، حَدَّثَنَا حَمَّادُ بْنُ زَيْدٍ، عَنْ عَمْرِو بْنِ دِينَارٍ، عَنْ جَابِرِ بْنِ زَيْدٍ، عَنِ ابْنِ عَبَّاسٍ، قَالَ قَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ " مَنْ نَسِيَ الصَّلاَةَ عَلَىَّ خَطِئَ طَرِيقَ الْجَنَّةِ " .
also referenced under: Hadith 908 (Reference) & Book 5, Hadith 961 (In-Book)