The Kaaba or the Holy House of God at Mecca
It was the first house for God's worship built for mankind; it was built by Adam, then was destroyed by time, then God inspired to Abraham to rebuild it together with his son Ishmael.
The Holy or Inviolable house of God at Mecca includes many signs indicative of its ancient time, like the Maqam of Abraham where the pilgrim pray two bowings or Rakat in prayer.
God instructed Adam to rebuild the house of God, and put the black meteorite as a land mark for Abraham to recognize the site of the Holy House at Mecca, and Prophet Abraham included that black stone in the building.
It does not mean that this black stone be worshipped, unless by the ignorant.
But the respect and sanctification of the House of God is a sanctification to God Himself.
Man can kiss the walls or the doors of the mosque, and it is not forbidden.
The forbidden thing is that man kisses the walls of the shrines and graves of prophets, imams, sheikhs, Jewish sages, Christian saints, which are the graves of servants of God, while glorification of the House of God and even putting gold in it is a good work not bad and not any sin.
Quran 3: 96. {The first House [of God's worship] appointed for people [for worship and pilgrimage] was that at Becca [: the old name of Mecca a];
it was blessed [by God as an answer to Abraham's prayer b],
and [as] guidance to the worlds c [because Mohammed was sent there and brought the Quran from his Lord, to be a light and guidance to all nations.]
3: 97. It includes [some] manifest signs [indicating its ancient time; among these is the present] Maqam of Abraham d;
whoever enters it e is in security [so that none may slay, wound or hurt him];
pilgrimage to the House [of God at Mecca] is a duty that men owe to God: concerning any [of them] who can afford the journey thereto f;
but whoso denies [his ability to go for pilgrimage g]; surely God does not need [the pilgrimage and the worship in His House of] all the worlds.}
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a Mecca was called Becca at the beginning, but the Arab later on changed its name into Mecca by time and passing of years and because of the mixing of the Arabic with the foreign languages, so they started to call it Mecca; and God called it by its old name in this aya.
It was Adam who built the House of God there, then it was destroyed after him, then Abraham rebuilt it on its foundations.
b Abraham blessed it and prayed for the prosperity and blessing for its dwellers.
c i.e. in it there has been guidance: where the worlds and nations are guided to the way of the truth.
d i.e. "the place where Abraham stood to pray": a place, present nowadays in the Holy Masjid at Mecca.
e Being fearful, he will be secure, for none will kill him in this place, neither any hurt may befall him.
f i.e. the pilgrimage is obligatory for anyone who can afford and go for pilgrimage.
g Anyone who conceals his wealth and says: I have no capability for the pilgrimage, and so he does not go for the pilgrimage …