大方廣圓覺修多羅了義經略疏 1.674

1.674

奢摩他，此云止，止是定義。下文釋云「至靜為行」。定有淺深，故標如來，簡非麁淺邪小之定。若亂心持戒，不堪入此觀門，故先定後戒。亦可文雖先後，修無先後。

Śamatha is translated here as 'calming'; calming has the meaning of samādhi. The text below explains it as 'taking utmost stillness as practice'. Samādhi has shallow and deep degrees, so it specifies 'the Tathāgata's' to distinguish it from coarse, shallow, deviant, or Hīnayāna samādhis. If one keeps the precepts with a scattered mind, one is unfit to enter this contemplative gateway; hence samādhi precedes precepts. It may also be that although the text has an order, in cultivation there is no prior or subsequent.