維摩經玄疏 4.67

4.67

答曰：不明聲聞作佛，五味之義不成。約不定中，得論四教也。釋迦出世所有經教，更不過此四教，攝此諸經，罄無不盡也。

Answer: Because it does not clarify that śrāvakas attain buddhahood, the meaning of the five flavors is not completed. It is with reference to the indeterminate that one may speak of the four teachings. All the scriptural teachings of Śākyamuni's appearance in the world do not go beyond these four teachings; these sūtras are encompassed completely, with nothing left out.