淨名經集解關中疏 2.126

2.126

天曰。言說文字皆解脫相　八天辯不思議解脫即文字也。文三。此初標文字即解脫。肇曰。舍利弗以言文為失故默然無言。謂順真解未能語。默齋致觸物無礙故天說等解以曉其意。

The goddess said: "Spoken words and letters are all the mark of liberation." (Eighth, the goddess explains that inconceivable liberation is identical to letters, in three parts. This is the first, identifying letters with liberation. [Seng]zhao says: "Śāriputra considered words and letters to be a fault and thus remained silent without speaking, thinking that this accorded with true liberation and that he could not yet speak. Silently aligning oneself so that encountering things meets no obstruction—the goddess therefore speaks of equal liberation to awaken his understanding.")