If anything ails him in that (second) age, let him say: 'Ye Prânas, ye Rudras, extend this my midday-libation unto the third libation, that I, the sacrificer, may not perish in the midst of the Prânas or Rudras.' Thus he recovers from his illness, and becomes whole.

In plain words: If a person falls sick in the middle years, he can ask his life-breaths, like the Rudras, to carry his life on into old age. By this prayer he gets well again.