Q. Why is it that we do not bow down to the ground in prayer anymore these days except on Rosh Hashanah and Yom Kippur? When did this practice stop? Does it have anything to do with not seeming like Muslims who still continue this practice?A. Throughout Tanach, we find that bowing, kneeling and full body prostration was part of prayer and the service of the Temple in Jerusalem. When the Beis Hamikdash was extant, men and women who were to hear there the holy name of Hashem from the mouth of the Cohen Gadol, would be required to prostrate.

A. Remah (O.H. 131: 8) mentions the existing prohibition of prostrating in our days. Mishna Berura (ibid. 40) explains that the Torah (Vayikra 26: 1) rules “Nor shall you install a kneeling-stone in your land, to bow down upon it.” This prohibition applies even when your intent is serving Hashem (if outside of the Beis Hamikdash) on a kneeling stone or even a stone floor. Mishna Berura quotes that Poskim maintain that this biblical prohibition is transgressed only when the two factors concur; full body prostration and it is on a stone floor. When only one of the two factor is involved the prohibition is rabbinical. Lastly, when one kneels on a non-stone floor, (or an intervening mat, floor cover or other material is placed between the body and the stone floor), there is no prohibition at all. Because of the complexity of what separates and permits and what is considered as part and parcel of the stone floor, it is customary today not to bow normally at all; only on Rosh Hashana and Yom Kipur

Additionally, the Talmud, (Megila 22b and Shulachan Aruch ibid.) indicates that a person of standing and stature is not allowed to kneel in his prayers unless he is convinced that his prayers will be answered. If such a person were to kneel in his petitions, and his prayers were not answered, it would seem, in the eyes of the people, as if Hashem is unfair and unjust, while in reality we don’t truly understand His ways.
Horav Shlomo Miller Shlit’a indicated that due to the concerns above mentioned, we usually avoid kneeling in our days. He also pointed out to the narrative told in Shoftim (Judges 7: 5) how Hashem instructed Yehoshua to test the people who should follow him to war by taking them for a drink by the water. “And every one that kneels upon his knees to drink, set him separately away from your group because they will not go with you, since they are thus accustomed to kneel before idols”. (Rashi ibid.)

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a