In a previous post, History of Salah 1, I talked about two stages of salah during the history of Islam (after the beginning of the Message.) The first stage was the morning and afternoon prayers, and the second stages was of the night prayer. There are two more stages.
The second stage is marked by a significant event--the Israa' and Mi'raaj, which took place roughly 3 years before hijrah. It was after the Muslims had suffered under sanctions, and after the Prophet Muhammad (ﷺ) had lost his beloved wife Khadeejah, who had supported him emotionally and financially, and after he lost his uncle Abu Talib who had protected him against his enemies, that he was taken on the Israa' and Mi'raaj. So after one of the lowest points in his life, the Prophet (ﷺ) is taken through the heavens and he receives the tremendous gift of the five salawat.
But first, Allah enjoined fifty prayers, every day and night, and it was when the Prophet (ﷺ) reached Musa on his way down that Musa instructed him to ask Allah for a reduction of that burden because it would be too much for his Ummah. So Muhammad (ﷺ) returned to Allah and asked that they be reduced, and Allah reduced it by five. Again, Muhammad (ﷺ) encountered Musa who told him to request another reduction. Allah granted the request and this continued until there were only 5 prayers remaining, at which point He told Muhammad (ﷺ) that these are five prayers every day and night, and for every prayer there is the reward of ten, so they are like fifty prayers. And Muhammad (ﷺ) did not want to ask for any less than that.
So that is how we get five daily prayers--it is a gift from Allah (SWT), and we can also understand the value of the salah, knowing that Allah (SWT) gave the Prophet (ﷺ) this obligation directly, and that it was prescribed in the heavens.
Another part of this stage is that along with the five daily prayers came the times of those prayers and the manner in which they are performed. The Angel Jibreel led the Prophet (ﷺ) in prayer to teach him the prayer times. On the first day he prayed all the prayers at the beginning of their times, and on the second day he delayed them until the end of their times, except the maghrib prayer which he prayed at the same time on both days, and then said that the time of each salah is between those two times.
Some other interesting things about this stage of salah is that the Qiblah was still towards Jerusalem, and that the prayers included 2 raka'ahs only (regardless of whether a person was traveling.) Also, it was allowed to talk during the salah. For example, if you came to the salah late, you might ask the person standing next to you, "Which raka'ah are we in?" and he might say "We're in the 2nd raka'ah." and it would be okay.
The fourth stage began the 2nd year after hijrah, and there were basically three changes to the salah. The first was changing the Qiblah from Jerusalem to Makkah. Additionally, the number of raka'ah was increased. We have this on a hadith from 'A'isha recorded yb Abu Dawud, that the prayer of the traveler was left as was originally prescribed, and the prayer of the resident was enhanced.
Lastly, talking during the salah was prohibited. Zayd ibn Arqaam narrated, "We used to talk while engaged in salah during the lifetime of Allah's Messenger, and one would talk with his companion regarding his needs in salah until this verse was revealed, 'Guard strictly the salah, especially the middle salah and stand before Allah qaaniteen (silently with obedience.)' We also have a hadith recorded by Muslim and narrated by Mu'awiyah ibn ul-Hakam, that the Messenger of Allah (ﷺ) said, "Talking is not befitting during the salah, for it consists only of glorifying Allah, declaring His Greatness, and the recitation of the Qur'an."