Waislamu wote wamekubaliana kwamba Sunnah ya Mtume Muhammad ﷺ ndiyo chanzo cha pili cha msingi cha Uislamu kilichoteremshwa, baada ya Qur'ani Tukufu. Sunnah sahihi imo ndani ya kazi kubwa ya fasihi ya Hadithi.1.

The Muslims are agreed that the Sunnah of the Prophet Muhammad (may Allah bless him and grant him peace) is the second of the two revealed fundamental sources of Islam, after the Glorious Qur'an. The authentic Sunnah is contained within the vast body of Hadith literature.1.

Hadithi (wingi: ahadith) ina sehemu mbili: matn (maudhui ya hadithi) na isnad (mnyororo wa wasimulizi). Maudhui yanaweza kuonekana ya kimantiki na yenye busara, lakini ili yakubalike yanahitaji isnad sahihi yenye wasimulizi wa kuaminika. 'Abdullah b. al-Mubarak (f. 181 AH), mmoja wa walimu mashuhuri wa Imam al-Bukhari, alisema: "Isnad ni sehemu ya dini. Kama isingekuwepo isnad, kila mtu angesema lolote alilopenda."2.

A hadith (pl. ahadith) is composed of two parts: the matn (text) and the isnad (chain of reporters). A text may seem to be logical and reasonable but it needs an authentic isnad with reliable reporters to be acceptable; 'Abdullah b. al-Mubarak (d. 181 AH), one of the illustrious teachers of Imam al-Bukhari, said, "The isnad is part of the religion: had it not been for the isnad, whoever wished to would have said whatever he liked."2.

Wakati wa uhai wa Mtume (Allah amrehemu na amsalimishe) na baada ya kufariki kwake, Masahaba wake walikuwa wakimtaja moja kwa moja wanaponukuu maneno yake. Tabi'un (Wafuasi wa Masahaba) nao walifuata mfano huo; baadhi yao walimnukuu Mtume ﷺ kupitia Masahaba, na wengine waliacha kutaja mpokezi wa kati - hadithi kama hiyo baadaye ilijulikana kama mursal. Ilionekana kwamba kiungo kilichokosekana kati ya Tabi'i na Mtume ﷺ kingeweza kuwa mtu mmoja, yaani Sahaba, au watu wawili, mtu wa ziada akiwa Tabi'i mkubwa aliyeisikia hadithi kutoka kwa Sahaba. Hili ni mfano wa jinsi haja ya kuhakiki kila isnadi ilivyotokea; Imam Malik (d. 179) alisema, "Wa kwanza kutumia isnadi alikuwa Ibn Shihab al-Zuhri" (d. 124).3.

During the lifetime of the Prophet (may Allah bless him and grant him peace) and after his death, his Companions (Sahabah) used to refer to him directly, when quoting his sayings. The Successors (Tabi'un) followed suit; some of them used to quote the Prophet (may Allah bless him and grant him peace) through the Companions while others would omit the intermediate authority - such a hadith was later known as mursal. It was found that the missing link between the Successor and the Prophet (may Allah bless him and grant him peace) might be one person, i.e. a Companion, or two people, the extra person being an older Successor who heard the hadith from the Companion. This is an example of how the need for the verification of each isnad arose; Imam Malik (d. 179) said, "The first one to utilise the isnad was Ibn Shihab al- Zuhri" (d. 124).3.

Sababu nyingine muhimu zaidi ilikuwa ni kutungwa kwa makusudi kwa hadithi na makundi mbalimbali yaliyoibuka miongoni mwa Waislamu, ili kuunga mkono misimamo yao (angalia baadaye, chini ya majadiliano kuhusu hadithi za maudu'). Ibn Sirin (d. 110), mmoja wa Tabi'un, alisema: "Hawakuwa wakiuliza kuhusu isnadi. Lakini fitna (vurugu, machafuko, hasa vita vya ndani) ilipotokea, walisema: Tutajie wapokezi wenu. Basi hadithi za Ahl al-Sunnah (Wafuasi wa Sunnah) zilikuwa zikikubaliwa, huku zile za Ahl al-Bid'ah (Wafuasi wa Uzushi) zisikubaliwe."4.

The other more important reason was the deliberate fabrication of ahadith by various sects which appeared amongst the Muslims, in order to support their views (see later, under discussion of maudu' ahadith). Ibn Sirin (d. 110), a Successor, said, "They would not ask about the isnad. But when the fitnah (trouble, turmoil, esp. civil war) happened, they said: Name to us your men. So the narrations of the Ahl al-Sunnah (Adherents to the Sunnah) would be accepted, while those of the Ahl al-Bid'ah (Adherents to Innovation) would not be accepted."4.