He used to explain the accusative particle "et" by saying that it implied the inclusion in the object of something besides that which is explicitly mentioned. However, in the sentence "You shall fear [et] the Lord your God", he did not explain the particle "et" before "the Lord," since he did not wish to cause any one else to share in the reverence due to God; he justified his inconsistency with the explanation that the omission in this passage was as virtuous as was his resort to interpretation in all the other passages.
He once explained the accusative particle "et" by saying it implied something beyond what's explicitly mentioned. Nevertheless, when discussing "You shall fear [et] the Lord your God," he didn't clarify "et" before "the Lord," since he wanted to avoid suggesting reverence for anyone else; he rationalized his inconsistency by claiming that omitting explanation in this instance was equally praiseworthy as his use of interpretation elsewhere.