Yoga Rahasya Chapter Two verse 45

sthiti-krama-anurodhena gṛhiṇām yoga-sādhane |
prāṇāyāmo mukhyatama iti me matam-uttamam ||

In the Sthiti Krama the most important Yoga Sādhana
for the householder, according to my view, is Prāṇāyāma.

sthiti - staying or remaining or being in any state or condition; maintenance of life;krama - sequence; order; series; regular arrangement; succession; progressing step by step; in regular course; gradually, by degreesgṛhastha - standing in the home; living or staying in any one's house; householderyoga - the act of yokingsādhana - means to accomplish; leading straight to a goal; guiding well; furtheringprāṇāyāma - extending the breathiti - thus; in this manner; something that has been said or thought; having so said; (it is used like a quotation mark)mata - a thought, idea, opinion, view, sentimentuttama - most elevated, principal; uppermost, highest, chief; best, excellent