Matsyapurana 45.4

45.4

syamantakaḥ prasenasya maṇiratnamanuttamam
pṛthivyāṃ sarvaratnānāṃ rājā vai so 'bhavanmaṇiḥ //

Prasena possessed Syamantaka, which was the best of all gems on the earth, and was known as the king of all gems. Prasena used always to wear his beautiful Syamantaka jewel on his breast and Kṛiṣṇa more than once expressed a desire to have it, but was refused by Prasena ; and even though Kṛiṣṇa was powerful to take it by force, he did not like to do that.—4-5.