While Bhīṣmadeva was describing occupational duties, the sun’s course ran into the northern hemisphere. This period is desired by mystics who die at their will.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
धर्मं प्रवदतस्तस्य स कालः प्रत्युपस्थितः । यो योगिनश्छन्दमृत्योर्वाञ्छितस्तूत्तरायणः
dharmaṃ pravadatastasya sa kālaḥ pratyupasthitaḥ | yo yoginaśchandamṛtyorvāñchitastūttarāyaṇaḥ
SB 1.9.29