J
Yes, there are some verses that have poor support from manuscript evidence and this may be one of them, although this text is a matter of some debate among scholars. Verses 3b and 4 are omitted from many major early manuscripts including the Sinaiticus, Ephraemi, Bezea, and the Alexandrinus. Some English translations such as the Revised and the NIV also omit this portion. It is however contained in a number of early Greek manuscripts. Whether or not this brief pericope actually belongs in the text of chapter five is uncertain but it seems that this narrative would be somewhat incomplete without some explanation as to why the infirmed man was seeking so earnestly to enter the pool and why he believed that this would cure his disease.