yā vai lasac-chrī-tulasī-vimiśra-
punāti lokān ubhayatra seśān
kas tāṁ na seveta mariṣyamāṇaḥ
yā—the river which; vai—always; lasat—floating with; śrī-tulasī—tulasī leaves; vimiśra—mixed; kṛṣṇa-aṅghri—the lotus feet of the Lord, Śrī Kṛṣṇa; reṇu—dust; abhyadhika—auspicious; ambu—water; netrī—that which is carrying; punāti—sanctifies; lokān—planets; ubhayatra—both the upper and lower or inside and outside; sa-īśān—along with Lord Śiva; kaḥ—who else; tām—that river; na—does not; seveta—worship; mariṣyamāṇaḥ—one who is to die at any moment.
The river [Ganges, by which the King sat to fast] carries the most auspicious water, which is mixed with the dust of the lotus feet of the Lord and tulasī leaves. Therefore that water sanctifies the three worlds inside and outside and even sanctifies Lord Śiva and other demigods. Consequently everyone who is destined to die must take shelter of this river.
Mahārāja Parīkṣit, just after receiving the news of his death within seven days, at once retired from family life and shifted himself to the sacred bank of the Yamunā River. Generally it is said that the King took shelter on the bank of the Ganges, but according to Śrīla Jīva Gosvāmī, the King took shelter on the bank of the Yamunā. Śrīla Jīva Gosvāmī's statement appears to be more accurate because of the geographical situation. Mahārāja Parīkṣit resided in his capital Hastināpura, situated near present Delhi, and the River Yamunā flows down past the city. Naturally the King would take shelter of the River Yamunā because she was flowing past his palace door. And as far as sanctity is concerned, the River Yamunā is more directly connected with Lord Kṛṣṇa than the Ganges. The Lord sanctified the River Yamunā from the beginning of His transcendental pastimes in the world. While His father Vasudeva was crossing the Yamunā with the baby Lord Kṛṣṇa for a safe place at Gokula on the other bank of the river from Mathurā, the Lord fell down in the river, and by the dust of His lotus feet the river at once became sanctified. It is especially mentioned herein that Mahārāja Parīkṣit took shelter of that particular river which is beautifully flowing, carrying the dust of the lotus feet of Lord Kṛṣṇa, mixed with tulasī leaves. Lord Kṛṣṇa's lotus feet are always besmeared with the tulasī leaves, and thus as soon as His lotus feet contact the water of the Ganges and the Yamunā, the rivers become at once sanctified. The Lord, however, contacted the River Yamunā more than the Ganges. According to the Varāha Purāṇa, as quoted by Śrīla Jīva Gosvāmī, there is no difference between the water of the Ganges and the Yamunā, but when the water of the Ganges is sanctified one hundred times, it is called the Yamunā. Similarly, it is said in the scriptures that one thousand names of Viṣṇu are equal to one name of Rāma, and three names of Lord Rāma are equal to one name of Kṛṣṇa.
Link to this page: https://prabhupadabooks.com/sb/1/19/6