Yoga Rahasya Chapter One verse 89

āsaneṣu yathā na-eva kramasya niyamaḥ kṛtaḥ |
prathama-abhyāsa-asinastadvat prāṇāyāmeṣu sarvataḥ ||

Just as in Āsana practice,
proper procedure should never be given up,
beginners in doing Prāṇāyāma,
should always follow the correct procedure.

āsana - particular posture; sitting, sitting down; seat, place, stool; abiding, dwellingyathā - according asna - no; not; nor, neithereva - indeed, truly, really; thus; so, just so, exactly sokrama - a step; progressing step by step, a particular manner or method of reading and writing Vedic texts; sequence; order; series; regular arrangement; succession; in regular course; gradually, by degreesniyama - observances; restraint of the mind; a rule or precept; obligation; restraining, checking, holding backkṛta - done; made; accomplished; performedprathamā - earliest, primary, original, prior, former; foremost, first, preceding, initial; chief, principal, most excellentabhyāsa - practice; the effort of the mind to remain in its unmodified condition of purity ; repeated or permanent exercise, discipline, use, habit, custom;prāṇāyāma - extending the breath