Beginning with the abdomen and proceeding through the heart, they (mystic yogis) reach the top of the head and pass through the brahma-randhra, the hole at the top of the skull

Expressions researched:
"Beginning with the abdomen and proceeding through the heart, they reach the top of the head and pass through the brahma-randhra, the hole at the top of the skull"

CC Madhya-lila

Beginning with the abdomen and proceeding through the heart, they reach the top of the head and pass through the brahma-randhra, the hole at the top of the skull. Thus these yogīs attain the perfectional platform and do not enter the cycle of birth and death again.

CC Madhya 24.166, Translation and Purport:

"'Those who follow the path of great, saintly mystic yogīs take to the yogic gymnastic process and begin worshiping from the abdomen, where it is said that Brahman is located. Such people are called śārkarākṣa, which means that they are situated in the gross bodily conception. There are also followers of the ṛṣi known as Āruṇa. Following his path, they observe the activities of the arteries. Thus they gradually rise to the heart, where subtle Brahman, Paramātmā, is situated. They then worship Him. O unlimited Ananta! Better than these persons are the mystic yogīs who worship You from the top of their heads. Beginning with the abdomen and proceeding through the heart, they reach the top of the head and pass through the brahma-randhra, the hole at the top of the skull. Thus these yogīs attain the perfectional platform and do not enter the cycle of birth and death again.'"

This is a quotation from Śrīmad-Bhāgavatam (10.87.18).