Mahidâsa Aitareya (the son of Itarâ), who knew this, said (addressing a disease): 'Why dost thou afflict me, as I shall not die by it?' He lived a hundred and sixteen years (i.e. 24+44+48). He, too, who knows this lives on to a hundred and sixteen years.

In plain words: The sage Mahidâsa Aitareya knew this teaching. He told a sickness, "Why trouble me? I will not die from you." He lived 116 years, and the passage says anyone who knows this will live that long too.