Itibar
A single isnad is a witness. The critic lays a second road beside it — same companion (mutabi) or another companion with the same meaning (shahid). Shared names are the trunk. Names that appear on only one side are the test.
طَلَبُ الْعِلْمِ فَرِيضَةٌ عَلَى كُلِّ مُسْلِمٍ
Shahid — another Companion, same meaning
Ibn Majah 224 — Anas, through Hafs.
رَسُولُ اللَّهِ ﷺ
The Messenger of Allah ﷺ
أَنَسُ بْنُ مَالِك
Anas ibn Malikthis road only
مُحَمَّدُ بْنُ سِيرِين
Muhammad ibn Sirinthis road only
كَثِيرُ بْنُ شِنْظِير
Kathir ibn Shinzhirthis road only
حَفْصُ بْنُ سُلَيْمَان
Hafs ibn Sulaymanthis road only
هِشَامُ بْنُ عَمَّار
Hisham ibn Ammarthis road only
مُحَمَّدُ بْنُ يَزِيدَ ابْنُ مَاجَه
Muhammad ibn Yazid ibn Majahthis road only
Muslim — Abu Hurairah, a different wording.
رَسُولُ اللَّهِ ﷺ
The Messenger of Allah ﷺ
أَبُو هُرَيْرَة
Abu Hurairahthis road only
أَبُو صَالِحٍ السَّمَّان
Abu Salih al-Sammanthis road only
سُلَيْمَانُ الْأَعْمَش
Sulayman al-A'mashthis road only
مُسْلِمُ بْنُ الْحَجَّاج
Muslim ibn al-Hajjajthis road only
Names on both roads1
Ibn Majah 224 carries the famous sentence through Hafs ibn Sulayman — a reciter of the Qur’an, weak in hadith. Muslim’s report (a path of knowledge) is another Companion and another sentence. That is a shahid of meaning: the duty to learn is sound. It does not make Hafs’s isnad sahih, and it does not carry the extra clause about swine and pearls.