Prāṇāyāma
Śanaiḥ Śanaiḥ — Slowly, Slowly
Haṭha Yoga Pradīpikā's warning on the pace of prāṇāyāma: the breath is tamed the way a wild animal is tamed — gradually.
Slowly Slowly — Hatha Yoga Pradipika 2.15 (2.16 in some editions)
यथा सिंहो गजो व्याघ्रो भवेद्वश्यः शनैः शनैः। तथैव सेवितो वायुरन्यथा हन्ति साधकम्॥
yathā siṁho gajo vyāghro bhaved vaśyaḥ śanaiḥ śanaiḥ | tathaiva sevito vāyuranyathā hanti sādhakam ||
Just as a trainer tames a wild lion, elephant or tiger gradually, so should the practitioner control the prana cautiously by the practice of kumbhaka, or else it might kill him. — Swami Muktibodhananda translation (Bihar School of Yoga)
Just as lions, elephants and tigers are controlled by and by, so the breath is controlled by slow degrees, otherwise (i.e., by being hasty or using too much force) it kills the practiser himself. — Pancham Sinh translation (1915)
Just as a lion, an elephant, a tiger is brought under one's will slowly, slowly — so too the breath, when it is tended. Otherwise it kills the practitioner. — my own, kept literal
Śanaiḥ śanaiḥ (शनैः शनैः): slowly, slowly. Gradually, gradually. The verse does not soften the stakes — anyathā hanti sādhakam (अन्यथा हन्ति साधकम्), "otherwise it kills the practitioner." The breath is compared to a lion, an elephant, a tiger. You don't rush a tiger.
Notice where Svātmārāma puts this verse: in the section introducing prāṇāyāma, before teaching a single technique. The placement is the teaching. It is one of the most frequently cited warnings in the traditional texts, and it comes first because the techniques work. Go slowly. The pace is not a concession — it is the method.