Matsya Purana — Manvantaras
मैथुनस्यासमाचारो जल्पनाच्चिन्तनात्तथा निवृत्तिर्ब्रह्मचर्यं च तदेतच्छमलक्षणम् //
maithunasyāsamācāro jalpanāccintanāttathā nivṛttirbrahmacaryaṃ ca tadetacchamalakṣaṇam //
Refraining from sexual intercourse, and likewise withdrawing from idle talk and from brooding thoughts—this is brahmacarya; and this is the defining mark of śama (inner tranquility and self-restraint).
This verse does not discuss pralaya; it defines ethical self-restraint (śama) through brahmacarya, emphasizing control of action, speech, and thought.
It frames brahmacarya broadly as disciplined restraint—avoiding sexual indulgence, idle speech, and obsessive thinking—virtues that support a king’s governance (self-mastery) and a householder’s moral stability.
No vastu/temple rule is stated; the ritual takeaway is inner purification—brahmacarya and control of speech/thought are presented as core disciplines that underpin successful vrata, japa, and worship.