Nanda Maharaja was his (Vasudeva's) friend, but out of deep affection and attachment for his own son, he knowingly did this - placed his own son on the bed of Yasoda, picked up Nanda Maharaja's daughter

Expressions researched:
"Nanda Mahārāja was his friend, but out of deep affection and attachment for his own son, he knowingly did this"

Srimad-Bhagavatam

SB Canto 10.1 to 10.13

Vasudeva knew very well that as soon as the daughter was in the prison house of Kaṁsa, Kaṁsa would immediately kill her; but to protect his own child, he had to kill the child of his friend. Nanda Mahārāja was his friend, but out of deep affection and attachment for his own son, he knowingly did this. Śrīla Viśvanātha Cakravartī Ṭhākura says that one cannot be blamed for protecting one's own child at the sacrifice of another's.

SB 10.3.51, Translation and Purport

When Vasudeva reached the house of Nanda Mahārāja, he saw that all the cowherd men were fast asleep. Thus he placed his own son on the bed of Yaśodā, picked up her daughter, an expansion of Yogamāyā, and then returned to his residence, the prison house of Kaṁsa.

Vasudeva knew very well that as soon as the daughter was in the prison house of Kaṁsa, Kaṁsa would immediately kill her; but to protect his own child, he had to kill the child of his friend. Nanda Mahārāja was his friend, but out of deep affection and attachment for his own son, he knowingly did this. Śrīla Viśvanātha Cakravartī Ṭhākura says that one cannot be blamed for protecting one's own child at the sacrifice of another's. Furthermore, Vasudeva cannot be accused of callousness, since his actions were impelled by the force of Yogamāyā.