Sforno on Exodus 34:5/ספורנו על שמות ל״ד:ה׳

1ויתיצב עמו שם. Moses stood there close to G’d, as he had been commanded in verse 2.

2ויקרא, now the subject is G’d.

3'בשם ה, By calling out G’d indicated that he was about to carry out some specifically Divine activities.