by Imâm an-Nawawî (d. 676 AH / 1299 CE) All Praise is due to Allaah, the Lord of the Worlds, the [One Who] Sustains the Heavens and Earths, Director of all that is created, who sent the Messengers (may the peace and blessings of Allaah be upon all of them) to rational beings, to guide them and explain the religious laws to them with clear proofs and undeniable arguments. I praise Him for all of His bounties. I ask Him to increase His grace and generosity. I bear witness that there is none worthy of worship except Allaah alone, who has no partner, the One, Who Subdues, the Generous, the Forgiving. I bear witness that our leader Muhammad is His servant and Messenger, His beloved and dear one, the best of all creation. He was honoured with the Glorious Qur'aan that has been an enduring miracle throughout the years. He was also sent with his guiding Sunnah that shows the way for those who seek guidance. Our leader Muhammad has been particularized with the characteristic of eloquent and pithy speech, and simplicity and ease in the religion. May the peace and blessings of Allaah be upon him, the other Prophets and Messengers, all of their families and the rest of the righteous.
To proceed :
We have narrated, through many chains (isnaad, pl. asaaneed) and various narrations, from Ali ibn Abee Taalib, Abdullaah ibn Mas'ood, Mu'aadh ibn Jabal, Abu ad-Dardaa, [Abdullaah] ibn 'Umar, [Abdullaah] ibn 'Abbaas, Anas ibn Maalik, Abu Hurairah and Abu Sa'eed al-Khudree - May Allaah be pleased with all of them - that the Messenger of Allaah (sallAllaahu alayhi wa sallam) said : "Whoever preserves for my Ummah forty hadeeth related to the religion, Allaah will then resurrect him in the company of the pious and the scholars." Another narration states : "Allaah will raise him as an erudite and learned scholar". In the narration from Abu ad-Dardaa, it is stated : "On the Day of Resurrection, I will be an intercessor and witness for him". In the narration from Ibn Mas'ood it is stated that the Prophet (sallAllaahu alayhi wa sallam) said : "It will be said to him 'Enter Paradise through any door you wish'". In the narration from ibn 'Umar, one finds the words : "He will be recorded among the company of the scholars and will be resurrected in the company of the martyrs". [However] The scholars of hadeeth agree that, although this hadeeth has numerous chains, it is weak [ie. da'eef, and hence cannot be used as a sharee'ah proof].
The scholars (may Allaah be pleased with them) have compiled innumerable works of this nature [ie. collections of forty hadeeth]. The first one that I know of who compiled such a work was Abdullaah ibn al-Mubaarak [a taabi'ee, rahimahu Allaah]. After him came ibn Aslam at-Toosee, a pious scholar. Then came al-Hasan ibn Sufyaan an-Nasaa'ee, Abu Bakr al-Aajurree, Abu Bakr Muhammad ibn Ibraaheem al-Asfahaanee, ad-Daaraqutnee, al-Haakim, Abu Nu'aim, Abu Abd-ir-Rahmaan as-Sulamee, Abu Sa'eed al-Maleenee, Abu 'Uthmaan as-Saaboonee, Abdullaah ibn Muhammad al-Ansaaree, Abu Bakr al-Baihaqee and countless others both from the earlier and later times.
I have turned to Allaah for guidance and prayed to Him while compiling these forty hadeeth, following the example of those Imaams and guardians of Islaam. The scholars have agreed that it is permissible to act in accordance with weak hadeeth that deal with the virtues of good deeds [ie not weak hadeeth that deal with rulings - ahkaam - or acts of worship]. Nonetheless, given that fact, I have not simply relied upon that [weak] hadeeth [mentioned above], in compiling this work. Instead, I am following the statement of the Prophet (sallAllaahu alayhi wa sallam) found in an authentic hadeeth : "Let him who was present among you inform those who are absent". The Prophet (sallAllaahu alayhi wa sallam) also said : "May Allaah make radiant the man who has heard what I said, preserved it in his memory and conveyed it in the way that he heard it".
[Note : What an-Nawawi is saying here is that many of the scholars before him have made collections of forty hadeeth, and hence he is following their good example and not simply following the weak hadeeth quoted above, thus showing that he considers it improper to base ones actions upon weak hadeeth alone.]
Scholars have compiled forty hadeeth on faith and belief (usool), on practical matters (furoo'), on jihaad, on austerity (zuhd), on etiquette (adaab), and even on sermons (khutbahs). All of these [collections] were concerning righteous aims. May Allaah be pleased with those who sought them. However I have found it best to collect together forty hadeeth which are more important than all of those. These forty hadeeth incorporate all of those separate topics. In fact, each hadeeth is by itself a great general precept from the foundations of the Religion. Some scholars state that all of Islaam revolves around these hadeeth. Some have said, about a particular hadeeth, that they are one-half of Islaam, one-third of Islaam and so forth.
I have committed myself to including only authentic hadeeth (saheeh or hasan) in these forty hadeeth. The majority of them are from Saheeh al-Bukhaaree or Saheeh Muslim. I have mentioned them without their chain of narrators in order for it to be easier to memorize them and thus more [people] will be able to benefit from them, Allaah willing. After the hadeeth, I included a section on the meanings of the obscure expressions found in the hadeeth.
Everyone who desires and looks forward to the Hereafter must be familiar with these hadeeth because they cover the most important aspects of the religion and offer direction to all forms of obedience of Allaah. This is clear to anyone who ponders these hadeeth.
I rely only upon Allaah and I entrust my affair only to Him. To Him is all Praise and Grace, from Him is Guidance and protection from error.