He (Krsna) can be known only by one who has His mercy. The Yadavas were all exceptionally learned and experienced, but in spite of knowing the Lord as the one who lives in everyone's heart, they could not understand that He is the Personality of Godhead

Expressions researched:
"He can be known only by one who has the mercy of the Lord. The Yādavas were all exceptionally learned and experienced, but in spite of their knowing the Lord as the one who lives in everyone's heart, they could not understand that He is the original Personality of Godhead"

SB Canto 3

The Yādavas were all exceptionally learned and experienced, but in spite of their knowing the Lord as the one who lives in everyone's heart, they could not understand that He is the original Personality of Godhead.

SB 3.2.9, Translation and Purport:

The Yadus were all experienced devotees, learned and expert in psychic study. Over and above this, they were always with the Lord in all kinds of relaxations, and still they were only able to know Him as the one Supreme who dwells everywhere.

In the Vedas it is said that the Supreme Lord or the Paramātmā cannot be understood simply by the strength of one's erudition or power of mental speculation: nāyam ātmā pravacanena labhyo na medhayā na bahunā śrutena (Kaṭha Upaniṣad 1.2.23). He can be known only by one who has the mercy of the Lord. The Yādavas were all exceptionally learned and experienced, but in spite of their knowing the Lord as the one who lives in everyone's heart, they could not understand that He is the original Personality of Godhead. This lack of knowledge was not due to their insufficient erudition; it was due to their misfortune. In Vṛndāvana, however, the Lord was not even known as the Paramātmā because the residents of Vṛndāvana were pure unconventional devotees of the Lord and could think of Him only as their object of love. They did not know that He is the Personality of Godhead. The Yadus, or the residents of Dvārakā, however, could know Lord Kṛṣṇa as Vāsudeva, or the Supersoul living everywhere, but not as the Supreme Lord. As scholars of the Vedas, they verified the Vedic hymns: eko devaḥ. .. sarva-bhūtādhivāsaḥ... antaryāmī... and vṛṣṇīnāṁ para-devatā. ... The Yadus, therefore, accepted Lord Kṛṣṇa as the Supersoul incarnated in their family, and not more than that.