on the authority of abu najeeh al-'irbaad ibn saariyah (radiallaahu anhu) who said :

it was related by abu dawood and at-tirmidhee, who said that it was a good and sound hadeeth.

explanation of hadeeth number 28

in some of the narrations of this hadeeth it occurs : "verily this is a farewell sermon, so what do you charge/entrust us with ?" to which the prophet sallallaahu alayhi wa sallam replied : "verily i have left you upon a white plain [ie clear guidance], its night is like its day, and none deviates from it except that he is destroyed". and in another narration, his (radiallaahu anhu) statement "a profound sermon" means that the sermon affected them and caused them to feel fear in their hearts, and brought tears to their eyes.

and his (sallallaahu alayhi wa sallam) statement "i counsel you to have taqwaa (fear) of allaah, and to listen and obey [your leader]" means the ruler, even if he may be a slave. and in some of the narrations it mentions "an ethiopian slave". some of the 'ulamaa have said that a slave cannot be the ruler, and that this has been mentioned by way of an example or supposition. and this is similar to his (sallallaahu alayhi wa sallam) statement "whosoever builds for allaah a masjid like a bird's nest, allaah builds for him a house in paradise". and a bird's nest cannot be a masjid, but this is given simply by way of an example. other 'ulamaa say that in this statement the prophet (sallallaahu alayhi wa sallam) is informing us that the rulership will become corrupt, and will be given to other than its rightful owners, until it is even given to the slaves. so if this were to occur then still listen and obey, in order to secure the lesser of two evils, which are putting up with a ruler who rules without right, or bringing about chaos and a great fitnah through revolt.

and his (sallallaahu alayhi wa sallam) statement : "verily he among you who lives long will see great controversy" is from amongst his (sallallaahu alayhi wa sallam) miracles, as he informed his companions of that which was to occur after him of differences and the spreading of evil. and he (sallallaahu alayhi wa sallam) was aware of this in complete detail, but he did not reveal all these details to every individual. rather he used to warn about it in a general fashion, but also explained it in detail to some individuals such as hudhayfah and abu hurayrah (radiallaahu anhumaa), and this is evidence to show their great position and status.

and as for his (sallallaahu alayhi wa sallam) statement "so you must keep to my sunnah" then the word 'sunnah' means the straight, correct and sound way which proceeds upon his normal/customary way, and that is the clear path. and "the sunnah of the khulafaa' ar-raashideen (the rightly guided caliphs), those who guide to the right way" are those in whom the guidance was contained, and they are the four by consensus of the muslims - abu bakr, and 'umar, and 'uthmaan and 'alee, may allaah be pleased with them all.

and the prophet (sallallaahu alayhi wa sallam) ordered us with clinging to the sunnah of the khulafaa' ar-raashideen for two reasons :
the first is in the form of taqleed (following without evidence) for the one who is incapable of making his own discernment/judgement.
the second is in the form of deciding that which is more correct when faced with a difference of opinion amongst the sahaabah themselves.

and as for his (sallallaahu alayhi wa sallam) statement "beware of newly invented matters [in the religion]" then know that such newly invented matters are of two types :
1) that matter which has no basis in the sharee'ah, and this is baatil [rejected] and blameworthy
2) that matter which has a parallel or similarity in the sharee'ah, then this is not blameworthy.
this is because the words 'newly invented matter' and 'bid'ah' are not deemed blameworthy purely on the basis of the words themselves, but due to their indicating opposition to the sunnah and calling towards misguidance, and so they are not considered to be unrestrictedly wrong. for example, 'umar (radiallaah anhu) reinstated the taraaweeh prayer and said "what an excellent bid'ah is this." it is to be noted here that the prophet (sallallaahu alayhi wa sallam) had led the taraaweeh prayer in congregation for a few days, but then discontinued it due to his fear that the people would think it obligatory. this condition remained throughout the khilaafah of abu bakr (radiallaahu anhu), until 'umar (radiallaahu anhu) restarted what the prophet (sallallaahu alayhi wa sallam) had already laid a precedent for. thus, he used the word bid'ah in a purely linguistic sense, and not in the shar'ee sense that is used for blameworthy things.

and allaah knows best.

summary :

• that one should speak in a way, when it is needed, that reaches the very hearts of the people
• that the sahaabah (radiallaahu anhum) cried when listening to the sermon, and hence it is not wrong to cry during sermons
• that the advice given in this hadeeth is parting advice from the prophet (sallallaahu alayhi wa sallam)
• that the first thing advised is to fear allaah (ie to have taqwaa)
• that one should obey the ameer ul-mu'mineen completely
• that obedience is due to the ameer ul-mu'mineen, no matter who becomes so (as long he fulfills its conditions)
• that there will be controversy and difference of opinion after the messenger sallallaahu alayhi wa sallam
• that in all cases of difference it is obligatory to stick to the sunnah, the way of the messenger (sallallaahu alayhi wa sallam) and to the way of the first four rightly guided caliphs
• that the messenger (sallallaahu alayhi wa sallam) has referred to his sunnah and that of the rightly guided caliphs as one thing, through his saying 'cling to it'
• that one must be extremely careful about new things in the deen
• that one must ensure that everything that one does as part of his religion indeed has proof for it in the qur'aan and sunnah
• that every invented matter in the deen (which has no basis in the sharee'ah) is a bid'ah, and bid'ah leads away from paradise and towards the hell fire, and hence there cannot be a "good bid'ah"
• that innovations can be in belief and in actions, and are manifestations of controversy