SB 4.23.22
vidhaya krtyam hradini-jalapluta
dattvodakam bhartur udara-karmanah
natva divi-sthams tridasams trih paritya
vivesa vahnim dhyayati bhartr-padau
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
After this, the Queen executed the necessary funerary functions and offered oblations of water. After bathing in the river, she offered obeisances to various demigods situated in the sky in the different planetary systems. She then circumambulated the fire and, while thinking of the lotus feet of her husband, entered its flames.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The entrance of a chaste wife into the flames of the pyre of her dead husband is known as saha-gamana, which means “dying with the husband.” This system of saha-gamana had been practiced in Vedic civilization from time immemorial. Even after the British period in India this practice was rigidly observed, but soon it degraded to the point that even when the wife was not strong enough to enter the fire of her dead husband, the relatives would force her to enter. Thus this practice had to be stopped, but even today there are still some solitary cases where a wife will voluntarily enter the fire and die with her husband. Even after 1940 we personally knew of a chaste wife who died in this way.