Wiping over the kuffs is permitted instead of removing it during ablution. The Prophet (PBUH) used to wipe over the top of his khuffs, and if one wipes over the back or the bottom of his khuffs; wiping is invalid.
How to wipe
The place where the wiping should be done is the top of the khuffs and what is required is what is understood by saying ‘to wipe’. In the hadith in which al-Mughirah ibn Shu'bah describes how the Prophet (peace be upon him) wiped over his khuffs during his ablution
:he said
Related by Ahmad, hadith No. 18,156; al-Tirmidhi, hadith No. 98
If one wipes over the bottom or the back of the khuffs and not the top, one does wrong and the wiping is invalid.
:Ali said
‘Had things in religion always been based on logic, the bottom of the khuffs would have been more appropriate to wipe upon than the top. I saw Allah’s messenger wiping over the top of his khuffs.’
Related by Abu Dawud, hadith No. 162; al-Bayhaqi in Al-Sunan al-Kubra, hadith oN1,386
Duration
There is a specific duration for wiping over the khuffs, which is one day and one night for a person staying in his home town or travelling a short distance that does not permit him to shorten his prayers. As for a traveller beyond the distance allowing shortening prayers, the duration is three days and nights.
:Ali said
‘Allah’s messenger permitted three days and nights for a traveller and one day and night for a resident.’
Related by Muslim, hadith No. 276