Matsya Purana — Glory of Tīrtha-Śrāddha: Best Times
श्राद्धसाधनकाले तु पाणिनैकेन दीयते तर्पणं तूभयेनैव विधिरेष सदा स्मृतः //
śrāddhasādhanakāle tu pāṇinaikena dīyate tarpaṇaṃ tūbhayenaiva vidhireṣa sadā smṛtaḥ //
At the time of performing the rites that constitute Śrāddha, the offering is to be given with one hand; but for Tarpaṇa it is to be performed with both hands. This rule is always remembered as the proper procedure.
This verse does not address Pralaya; it focuses on ritual discipline in ancestor rites, specifying correct hand-usage in Śrāddha and Tarpaṇa.
It directly guides gṛhastha-dharma (and by extension royal dharma) by prescribing precise ritual etiquette for Pitṛ-karmas: offer Śrāddha with one hand, and perform Tarpaṇa with both hands.
The significance is ritual-technical: correct performance (vidhi) depends even on bodily procedure—one-handed offering in Śrāddha, two-handed libation in Tarpaṇa—highlighting standardized Matsya Purana ritual rules.