Bhagavatapurana 6.10.33

6.10.33

dvau sammatāviha mṛtyū durāpau yadbrahmasandhāraṇayā jitāsuḥ /
kalevaraṃ yogarato vijahyād yadagraṇīrvīraśaye 'nivṛttaḥ //

33. "There are two desirable cases of death that are not easily the lot of all (1) that one, having controlled his breaths and successful in yoga practice, may in contemplation of Brahman cast off the body and (2) that a warrior fighting in front of the battle-field (the bed of warriors) gives up his ghost without turning his back."