The strength of the sanad is considered a condition in accepting a hadīth. However it should be known that judging the sanad of a specific hadith as weak does not necessarily mean the hadīth is weak in itself since it might have another isnād though an imam who might state that it has not been recieved except from this line of transmission. So, whoever finds a hadīth with a weak isnād, it is more inclusive to say that it is weak with this isnād but the text is not judged as weak without qualification. Therefore the rejection of the isnād does not necessitate the rejection of the hadīth. However, there are ahadīth which are not proved from the perspective of the isnād but when it is received from people to people they are satisfied with its authenticity and are in no need to ask for the isnād. There are many examples for this, such as the hadīth:

and the hadīth:

There are many other examples like this.