妙法蓮華經玄贊 10.192

10.192

釋名者，「藥」者能去疾之神功，「王」者有自在之威力；「本」者因由，「事」者體業。今此菩薩願為藥樹，療八塵之痼疾、除七漏之深痾，勢力無雙威神罕匹，故名藥王菩薩。今此品中敘彼本因修行之事，以利時會，名藥王菩薩本事品。

As for explaining the title: "Medicine" (bhaiṣajya) refers to the divine efficacy of being able to eliminate disease; "King" (rāja) refers to having sovereign and awe-inspiring power. "Ancient" (pūrva) refers to the causes and conditions; "Accounts" (yoga) refers to substance and activities. Now, this bodhisattva vowed to be a medicinal tree to cure the chronic afflictions of the eight dust-realms and eradicate the deep maladies of the seven outflows; his strength is matchless and his majesty rarely rivaled, hence he is named Bodhisattva Bhaiṣajyarāja. Now, in this chapter, the accounts of his cultivation in his original causal [state] are recounted in order to benefit the contemporary assembly; hence it is named "Ancient Accounts of Bodhisattva Bhaiṣajyarāja" Chapter.