Brihajjataka 7.2

7.2

nīce ato ardhaṃ hrasati hi tataś ca antarasthe anupāto horā tv aṃśa pratimam apare rāśi tulyaṃ vadanti/
hitvā vakraṃ ripu graha gatair hīyate sva tri bhāgaḥ sūrya ucchinna dyutiṣu ca dalaṃ projihya śukra arka putrau//(meṃ krāṃ)

In debilitation, [the longevity] indeed decreases to half of that; between them, the proportion is calculated; but the horā, some say, is equal to the degrees, while others say it is equal to the signs.
Except when retrograde, [the years] of planets situated in enemy houses are reduced by a third of their own [share]; and when their radiance is destroyed by the Sun, half [is lost], leaving aside Venus and Saturn.