Halakhah к Шаббат 5:7

The Sages further ordained that kiddush be recited over wine during the day, just before the morning meal. By beginning the meal with kiddush, it is apparent that this meal is significant and special, and it reminds us of the holiness of Shabbat. Since the basis of the obligation of the daytime kiddush is rabbinic, no special berakha was instituted in honor of Shabbat; only Ha-gafen is recited, though verses relating to Shabbat are customarily recited beforehand. The Shabbat-day kiddush is called “Kidusha Rabba” (the “great kiddush”) euphemistically, as the nighttime kiddush is more important (see Peninei Halakha: Shabbat 5:1-3 for more on these laws).