佛說觀佛三昧海經 1.19

1.19

「爾時難陀龍王懼燒此山，即大降雨澍如車軸，鳥肉散盡惟有心在，其心直下如前七返，然後還住金剛山頂。難陀龍王取此鳥心以為明珠，轉輪王得為如意珠。」

"At that time, Nandarājarāja, fearing the burning of these mountains, sends down a great downpour of rain like chariot axles. The bird's flesh is completely dispersed, leaving only its heart. Its heart descends directly, returning seven times as before, and then comes to rest on the peak of the Diamond Mountain. Nandarājarāja takes this bird's heart and turns it into a bright jewel; a cakravartin obtains it as a cintāmaṇi."