This is copied from the Jewish tradition in their synagogues directed towards the Qibla of Jerusalem. 

       A recess or niche in the wall of a masjid/mosque that indicates the Qibla, i.e. the direction of direction of salat/ prayers directed towards the Ka'ba that Muhammadans should face when praying. The wall is called the Qibla wall. The mihrab gives the impression of a door or a passage to Mecca. They vary in size but are usually ornately decorated. Mihrabs first appeared in the reign of the Umayyad khalif al-Walid I (705715).

               The mihrab is the position of the person leading the congregation in prayer, and is by most Muhammadan Muslims considered the most holy place in the mosque, even if a mihrab is not dedicated to Allah, but frequently to religious personalities. A mosque will normally have only one mihrab.

              The mihrab is considered by both Muslim and Western scholars as an element taken from churches, an element added to the mosque for architectural reasons. The mihrab was probably introduced in the 3rd century of Islam, in the 9th century CE.

             Mihrabs can be of wood, but is normally made out of masonry, and adorned with pillars  and very often come highly ornamented.

3: 37        Right graciously did her Lord accept her: He made her grow in purity and beauty; to the care of Zakariya was she assigned.  Every time that he entered (her) chamber [al Mihraba] to see her he found her supplied with sustenance.  He said: "O Mary! whence (comes) this to you?"  She said: "From Allah: for Allah provides sustenance to whom He pleases without measure."

       #379        Mary grew under Allah's special protection. Her sustenance, under which we may include both her physical needs and her spiritual food, came from Allah, and her growth was indeed a "goodly growth" which I have tried to express in the Text by the words "purity and beauty". Some aprocryphal Christian writings say that she was brought up in the Temple to the age of twelve like a dove, and that she was fed by angels#

19: 1        Kaf. Ha. Ya. `Ain.  Sad

       2        (This is) a recital of the Mercy of thy Lord to His Servant Zakariya.

       7        (His prayer was answered): "O Zakariya! We give thee good news of a son: his name shall be Yahya: on none by that name have We conferred distinction before."

      10        (Zakariya) said "O my Lord! give me a Sign." "Thy Sign" was the answer "shall be that thou shalt speak to no man for three nights although thou art not dumb."  

      11        So Zakariya came out to his people from his chamber [al Mihrab]: he told them by signs to celebrate Allah's praises in the morning and in the evening.

     12        (To his son came the command): "O Yahya! take hold of the Book with might": and We gave him wisdom even as a youth.

38: 20        We strengthened his kingdom and gave him wisdom and sound judgment in speech and decision.

       21        Has the Story of the Disputants reached thee? Behold they climbed over the wall of the private chamber [al Mihraba];

       #4171        This story or Parable is not found in the Bible, unless the vision here described be considered as equivalent to Nathan's parable in 11 Samuel, xi, and xii. Baidhawi would seem to favour that view, but other Commentators reject it. David was a pious man, and he had a well-guarded private chamber (mihrab) for Prayer and Praise#
       22         When they entered the presence of David and he was terrified of them they said: "Fear not: We are two disputants one of whom has wronged the other: decide now between us with truth and treat us not with injustice but guide us to the even Path.