नक्तं न कुर्यात् पित्र्याणि भुक्त्वा चैव प्रसाधनम्
naktaṁ na kuryāt pitryāṇi bhuktvā caiva prasādhanam
Bhishma said: “One should not perform the rites for the Pitṛs at night; and after eating, one should likewise not undertake ritual preparations or acts of ceremonial purification.”
भीष्म उवाच
Ritual acts—especially ancestral rites—must be performed at proper times and in a state of appropriate purity; night-time performance and post-meal ritual preparation are discouraged as contrary to prescribed discipline.
In Anuśāsana Parva, Bhishma instructs Yudhishthira on dharma and correct conduct, giving practical rules about śrāddha/Pitṛ-related observances and standards of cleanliness and timing.