One who stands before God in prayer should know that her existence and all of life’s blessings are dependent on God’s kindness and that God is not required to fulfill her requests; hence, she should stand before Him humbly. That is what the Sages meant when they said (Berakhot 10b): “One may not stand on a chair, on a stool, or on any other high place and pray, because there is no haughtiness before the Omnipresent, as it says (Tehilim 130:1): ‘From the depths I called You, Lord.’” The Talmud (Ta’anit 23b) relates a story about R. Yona who was known as a righteous person whose prayers were answered. When he was asked to pray for rain, he went to a low place in order to fulfill the verse: “From the depths I called You, Lord.” He prayed there until he was answered and rain began to fall. For that reason, it is customary in some congregations that the ĥazan’s place is lower. This also explains why the ĥazan is described as “descending before the ark” (“yored lifnei ha-teiva”).
As a rule, the Sages prohibited an elevated place higher than three tefaĥim (c. 24 cm) above the ground. However, in practice, it is forbidden to pray even on a less elevated place, for two reasons. First, one standing on a stepstool or rock even only one tefaĥ in height is worried about losing her balance and cannot have the proper kavana while praying. Second, if the floor is even, elevating oneself on pillows, cushions, or anything else suggests a sense of haughtiness, and it is improper to pray in such a manner. Nevertheless, praying on rugs and mats which are normally laid out on the floor is permitted le-khatĥila. Likewise, one who prays on uneven ground may stand on the elevated parts, as long as they are not three tefaĥim higher than the rest of their surroundings (Peninei Halakha: Prayer, ch. 3 n. 4).
A sick or elderly person who has trouble getting out of bed may pray in bed, even though it is elevated from the ground, for that does not display haughtiness.
If the high place stands on its own – for instance, it is wider than four amot by four amot (c. two meters by two meters) – one may pray on it, because it is not measured in relation to other places. Rather it is considered its own domain. Even an area which is smaller than four amot squared is considered to be its own domain if it is surrounded by partitions, and it is permissible to pray on it.