Brihat Parashara Hora Shastra
विंशोत्तरशतं पूर्णमायुः पूर्वमुदाहृतम् । कलै विंशोत्तरी तस्माद् दशा मुख्या द्विजोत्तम ॥ १४॥
The remaining Dashas will be of the Grahas in the order, given above. In Kali Yuga the natural life-span of a human being is generally taken, as 120 years. Therefore Vimshottari Dasha is considered to be the most appropriate and the best of all Dashas.
english translation
viMzottarazataM pUrNamAyuH pUrvamudAhRtam । kalai viMzottarI tasmAd dazA mukhyA dvijottama ॥ 14॥
hk transliteration by Sanscript