While Śrī Vyāsadeva was following his son, beautiful young damsels who were bathing naked covered their bodies with cloth, although Śrī Vyāsadeva himself was not naked. But they had not done so when his son had passed. The sage inquired about this, and the young ladies replied his son was purified and when looking at them made no distinction between male and female. But the sage made such distinctions.
Bhisma- Although he didnt do any penance, but Bhisma was granted the boon of Sweccha Mrityu (control over his own death — he could choose the time of his death) from his father, Shantanu. So, after getting defeated by Arjun, he laid on a bed of arrows and delayed his death by his own will.