Ignorantly performing the obligatory prayer before appointed it`s time
Question: If a person is ignorant about the time of the prayer and prays before its appointed time, then what is the ruling (of the prayer he has just performed)?
Response: A person`s (performance of the) prayer before it`s appointed time does not relinquish him of it`s obligation as Allaah (Subhaanahu wa Ta’aala) says:
{Verily, As-Salât (the prayer) is enjoined on the believers at fixed hours}, [Soorah an-Nisaa., Aayah 103]
And the Prophet (sal-Allaahu `alayhe wa sallam) has explained these times (fixed hours) in his saying:
((The time for the Zhuhr (prayer) is once the Sun has passed it`s highest point (zawaal)…))…and so on the hadeeth relates, [Transmitted by al-Bukhaaree, No.541]
So, based upon this, whoever performs the prayer before its appointed time then his (performance of the) prayer does not relinquish him from its obligation. However, (the performance of this obligatory prayer before its appointed time) is regarded as a voluntary prayer, meaning that it is rewarded as a voluntary prayer and he is required to repeat the (obligatory) prayer at it`s (appointed) time, and Allaah has the complete knowledge.
Shaykh Ibn ‘Uthaymeen
I`laam al-Mu`aasireen bi-Fataawa Ibn `Uthaymeen – Page 47 source:fatwaonline.com