Hadithcore
Sahih al-Bukhari, 4940
sahih

Narrated Ibn `Abbas:

(as regards the Verse):--'You shall surely travel from stage to stage (in this life and in the Hereafter).' (It means) from one state to another. That concerns your Prophet.

حَدَّثَنَا سَعِيدُ بْنُ النَّضْرِ، أَخْبَرَنَا هُشَيْمٌ، أَخْبَرَنَا أَبُو بِشْرٍ، جَعْفَرُ بْنُ إِيَاسٍ عَنْ مُجَاهِدٍ، قَالَ قَالَ ابْنُ عَبَّاسٍ ‏{‏لَتَرْكَبُنَّ طَبَقًا عَنْ طَبَقٍ‏}‏ حَالاً بَعْدَ حَالٍ، قَالَ هَذَا نَبِيُّكُمْ صلى الله عليه وسلم‏.‏

References2 variants
In-Book Reference
Book 65, Hadith 461
USC-MSA web (English) reference
Vol. 6, Book 60, Hadith 464 (deprecated numbering scheme)