All praise is due to Allah the Lord of the universe.May the peace and blessings of Allah be upon all His Prophets and Messengers
The above is the evidence for observing five daily prayer in Islam:
Allah (S.W.T) stated clearly in Q17:78"Establish the prayer,at the decline of the sun till the darkness of the night and Qur'an at dawn,indeed the Qur'an at the dawn is ever witnessed.
In the above verse Allah(S.W.T) ordered all muslim faithfuls to observe solat from thet decline of the i.e from around 12:50 which is when the first prayer starts and then the second prayer comes before sunset.In the above verse Allah(S.W.T) used the word 'till' meaning the gap between the decline of the sun includes more than one prayer,the 3rd prayer which is the sunset prayer comes and then the 4th comes when it becomes dark and then Allah(S.W.T) mentioned the Qur'an at dawn which means the dawn prayer,Allah(S.W.T) using the phrase "Qur'an at dawn" is simply explaining that among all the five daily prayers,the dawn is one we spend more time reciting the Qur'an than anyother prayer.

This should enlighten everyone