SB 10.56.24
asit tad asta-vimsaham
itaretara-mustibhih
vajra-nispesa-parusair
avisramam ahar-nisam
Translation:
The fight went on without rest for twenty-eight days, the two opponents striking each other with their fists, which fell like the cracking blows of lightning.
Purport:
Srila Visvanatha Cakravarti points out that the fight continued day and night without intermission.