How did prayer ordain?

Narrated Abu Dhar: Allah's Apostle said, "While I was at Mecca
the roof of my house was opened and Gabriel descended, opened
my chest, and washed it with Zamzam water. Then he brought a
golden tray full of wisdom and faith and having poured its
contents into my chest, he closed it. Then he took my hand and
ascended with me to the nearest heaven, when I reached the
nearest heaven, Gabriel said to the gatekeeper of the heaven,
'Open (the gate).' The gatekeeper asked, 'Who is it?' Gabriel
answered: 'Gabriel.' He asked, 'Is there anyone with you?'
Gabriel replied, 'Yes, Muhammad I is with me.' He asked, 'Has
he been called?' Gabriel said, 'Yes.' So the gate was opened
and we went over the nearest heaven and there we saw a man
sitting with some people on his right and some on his left.
When he looked towards his right, he laughed and when he
looked toward his left he wept. Then he said, 'Welcome! O
pious Prophet and pious son.' I asked Gabriel, 'Who is he?' He
replied, 'He is Adam and the people on his right and left are
the souls of his offspring. Those on his right are the people
of Paradise and those on his left are the people of Hell and
when he looks towards his right he laughs and when he looks
towards his left he weeps.' Then he ascended with me till he
reached the second heaven and he (Gabriel) said to its
gatekeeper, 'Open (the gate).' The gatekeeper said to him the
same as the gatekeeper of the first heaven had said and he
opened the gate. Anas said: "Abu Dhar added that the Prophet
met Adam, Idris, Moses, Jesus and Abraham, he (Abu Dhar) did
not mention on which heaven they were but he mentioned that he
(the Prophet ) met Adam on the nearest heaven and Abraham on
the sixth heaven. Anas said, "When Gabriel along with the
Prophet passed by Idris, the latter said, 'Welcome! O pious
Prophet and pious brother.' The Prophet asked, 'Who is he?'
Gabriel replied, 'He is Idris." The Prophet added, "I passed
by Moses and he said, 'Welcome! O pious Prophet and pious
brother.' I asked Gabriel, 'Who is he?' Gabriel replied, 'He
is Moses.' Then I passed by Jesus and he said, 'Welcome! O
pious brother and pious Prophet.' I asked, 'Who is he?'
Gabriel replied, 'He is Jesus. Then I passed by Abraham and he
said, 'Welcome! O pious Prophet and pious son.' I asked
Gabriel, 'Who is he?' Gabriel replied, 'He is Abraham. The
Prophet added, 'Then Gabriel ascended with me to a place where
I heard the creaking of the pens." Ibn Hazm and Anas bin Malik
said: The Prophet said, "Then Allah enjoined fifty prayers on
my followers when I returned with this order of Allah, I
passed by Moses who asked me, 'What has Allah enjoined on your
followers?' I replied, 'He has enjoined fifty prayers on
them.' Moses said, 'Go back to your Lord (and appeal for
reduction) for your followers will not be able to bear it.'
(So I went back to Allah and requested for reduction) and He
reduced it to half. When I passed by Moses again and informed
him about it, he said, 'Go back to your Lord as your followers
will not be able to bear it.' So I returned to Allah and
requested for further reduction and half of it was reduced. I
again passed by Moses and he said to me: 'Return to your Lord,
for your followers will not be able to bear it. So I returned
to Allah and He said, 'These are five prayers and they are all
(equal to) fifty (in reward) for My Word does not change.' I
returned to Moses and he told me to go back once again. I
replied, 'Now I feel shy of asking my Lord again.' Then
Gabriel took me till we '' reached Sidrat−il−Muntaha (Lote
tree of; the utmost boundary) which was shrouded in colors,
indescribable. Then I was admitted into Paradise where I found
small (tents or) walls (made) of pearls and its earth was of
musk." Al-Bukhari V. 1-345.