Abū Ja’far reports:
Whenever Ibn ‘Umar – Allāh be pleased with him – heard a ḥadīth from Allāh’s Messenger – Allāh’s praise and peace be upon him – he never went beyond it, and he never fell short of it.
Ibn Mājah, Al-Sunan, ḥadīth #4. Shaykh Al-Albānī graded this narration ṣaḥīḥ in his edition of the Sunan.
Shaykh Al-Albānī explained that ‘he never went beyond it’ means: he never added anything to what was in the ḥadīth or overstepped the bounds of the ḥadīth; and ‘he never fell short of it’ means: he never neglected what was in the ḥadīth.