The ‘common link’ is not a newly coined term. Its history goes back to the middle of the twentieth century when Joseph Schacht first used it. Schacht, who was mainly concerned with the dating of hadiths, discovered a peculiar phenomenon in their isnāds: the ‘common transmitters’. If different isnāds of a given hadith are gathered and put together, almost all of them meet at a certain point at a common transmitter, whom he named the ‘common link’, and then through a single strand reach back to an authority such as a Companion or the Prophet himself. According to Schacht, ‘the existence of a significant common link (N.N.) in all or most isnāds of a given tradition would be a strong indication in favour of its having originated in the time of N.N.’. In other words, he believed that drawing on information obtained through the common link one can identify the origin of that particular hadith in terms of time and place. From his time onwards, ‘the common link’ has played a prominent role in modern hadith studies and has been used by those scholars who would date hadiths based on isnād analysis.

But was this phenomenon recognised by Muslim hadith scholars and traditionists (muḥaddithūn), and can one find some traces of this recognition in the Islamic hadith literature as well? Hadith scholars have coined a plethora of technical terms (muṣṭalaḥāt al-ḥadīth) to define the various features of hadiths and the qualifications of their transmitters. Is it possible to find amongst them some terms that, in one way or another, correspond to the common link or be considered as its equivalent?

In his prominent study, Schacht notices that Muslim hadith scholars already recognised this phenomenon: