One who is asked about knowledge but conceals it Sunan Ibn Majah 263
Arabic hadith text
حَدَّثَنَا الْحُسَيْنُ بْنُ أَبِي السَّرِيِّ الْعَسْقَلاَنِيُّ، حَدَّثَنَا خَلَفُ بْنُ تَمِيمٍ، عَنْ عَبْدِ اللَّهِ بْنِ السَّرِيِّ، عَنْ مُحَمَّدِ بْنِ الْمُنْكَدِرِ، عَنْ جَابِرٍ، قَالَ قَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ " إِذَا لَعَنَ آخِرُ هَذِهِ الأُمَّةِ أَوَّلَهَا فَمَنْ كَتَمَ حَدِيثًا فَقَدْ كَتَمَ مَا أَنْزَلَ اللَّهُ "
Translation
It was narrated that Jabir said
"The Messenger of Allah said: 'When the last people of this Ummah curse the first, (at that time) whoever conceals a Hadith will be concealing what Allah has revealed.'" (Maudu')