Abraham was the first person to be given the Salat and taught how to perform this sacred duty.
[21:72] And we granted him (Abraham) Isaac and Jacob as a gift, and we made them both righteous.
(٧٢) وَوَهَبْنَا لَهُ إِسْحَاقَ وَيَعْقُوبَ نَافِلَةً وَكُلًّا جَعَلْنَا صَالِحِينَ
[21:73] We made them imams who guided in accordance with our commandments, and we taught them how to work righteousness, and how to observe the Contact Prayers (Salat) and the obligatory charity (Zakat). To us, they were devoted worshipers.
(٧٣) وَجَعَلْنَاهُمْ أَئِمَّةً يَهْدُونَ بِأَمْرِنَا وَأَوْحَيْنَا إِلَيْهِمْ فِعْلَ الْخَيْرَاتِ وَإِقَامَ الصَّلَاةِ وَإِيتَاءَ الزَّكَاةِ وَكَانُوا لَنَا عَابِدِينَ
Muhammad was then instructed to follow the religion, and more specifically, the religious practices and rites of Abraham, milat Ibrahim.
[16:123] Then we inspired you (Muhammad) to follow the religion of Abraham,* the monotheist; he never was an idol worshiper.
(١٢٣) ثُمَّ أَوْحَيْنَا إِلَيْكَ أَنِ اتَّبِعْ مِلَّةَ إِبْرَاهِيمَ حَنِيفًا وَمَا كَانَ مِنَ الْمُشْرِكِينَ
This indicates the Salat, Zakat, Sayem (Fasting), Hajj have all been in existence since the time of Abraham, and that Muhammad and the rest of the prophets and messengers who came after Abraham were not informed how to do these practices, but simply just had to maintain and observe these rites e.g. aquim Salat.
[2:3] who believe in the unseen, observe the Contact Prayers (Salat),* and from our** provisions to them, they give to charity.
(٣) الَّذِينَ يُؤْمِنُونَ بِالْغَيْبِ وَيُقِيمُونَ الصَّلَاةَ وَمِمَّا رَزَقْنَاهُمْ يُنْفِقُونَ
One question that comes up when presented with this information is: if we are doing the Salat exactly as Abraham was doing it thousands of years ago, how do we account for the possible language differences between Arabic and the language Abraham spoke?
While we do not know definitively what language Abraham spoke there is a fair amount of confidence that it was a Semitic language, if not the original Semitic language. The Semitic language family consists of dozens of distinct languages including the languages of the monotheistic religions: Hebrew, Aramaic, and Arabic. Due to their common origin, these languages share a lot of the same vocabulary, syntax, and grammar.
While the writing structures between these languages can be quite distinct, the common origin of these languages becomes a lot more apparent when observing the spoken form. For example, take the word “peace.” It is salām– in Arabic, šlām-āʼ in Aramaic, šālôm in Hebrew and sliem in Maltese. “House” is another good example, as it’s bayt– in Arabic, bayt-āʼ in Aramaic, báyiṯ in Hebrew and bejt in Maltese.
An interesting observation is that if we translate the Arabic Fatehah from the to Hebrew or Aramaic we see that the spoken form are incredibly similar. A January 2004 article from the Submitters Perspective referenced the HA PATCHAH prayer which takes passages out of the Old Testament and Jewish prayers that correspond with the verses from the Fãtehah and the similarities in language are very clear.
HA PATCHAH (THE OPENING PRAYER)
BE SHEM ELAH HA RAHAMIM
In the name of God, the Most Gracious (Ezr.5:1; Dan.9:9)
ELOHEINU RIBOHN HA-OLAMIM
All praise be to God, Lord of the universe (Jewish liturgy)
HA RAHAMIM
The Most Gracious (Dan.9:9)
MELEK YOM HA DIN
Master of the Day of Judgment (Jewish terminology)
ELEKHA ADONAY EQARA WE EL ADONAY ET HANAN
To you, O Lord, I implore; and to my Lord, I seek help (Psalm 30:9)
HEHENI BE ORACH MISHOR
Guide us to the straight path (Psalm 27:11)
ALEKHET BE DEREHU WE LEYAREH ITTO
The way of life according to His path by reverencing Him (Deut 8:6)
LE HALAK BE ETSAH RISHAH WE LA SAGHAH
Not by the advice of the cursed, nor of the strayers (Psalm 119:21)

If you happen to know anyone who understands the Hebrew Bible and recite the Arabic Fatehah to them, you will notice that they will be able to understand nearly the entire seven verses without knowing any Arabic.
The Syriac language, a dialect of Aramaic spoken today in the Mesopotamian Plateau between Syria and Iraq, was once used widely throughout the Middle East. The Gospels were translated into Syriac early on, and Syriac studies today help document the historical relationships among Jews, Christians, and Muslims. In the book “The Qur’an Misinterpreted, Mistranslated, and Misread: The Aramaic Language of the Quran” it stated on page 109:
“There are Qur’anic verses that are easily understood by a Syriac speaking person, because the dialect of certain passages is similar to the vernacular Syriac of South East Turkey (Tur Abdin region). For example, the first chapter of “al-Fatiha”, every single word in that chapter, corresponds with the vernacular Syriac;”

The Danish linguist Holger Pedersen (1867-1953) explained in The Discovery of Language that “Hebrew, Aramaic, and Akkadian languages had all undergone significant linguistic degeneration. Only Classical Arabic, due to its relative isolation in the Arabian peninsula, remained closer to the old stratum of the ‘Semitic’ form of the language.”
This can explain why the Christians and Jews have lost the Salat, while this practice has been maintained by the Arabs.
[19:58] These are some of the prophets whom GOD blessed. They were chosen from among the descendants of Adam, and the descendants of those whom we carried with Noah, and the descendants of Abraham and Israel, and from among those whom we guided and selected. When the revelations of the Most Gracious are recited to them, they fall prostrate, weeping. [19:59] After them, He substituted generations who lost the Contact Prayers (Salat), and pursued their lusts. They will suffer the consequences.
This shows that it is not a stretch to consider that the Fatehah that Abraham recited could have been linguistically equivalent to the Fatehah we have today. It is interesting to note that since the Arab people came from the lineage of Ismail and since they were more isolated from other influences that their language was better preserved to the original language of Abraham as the other Semitic languages.
[19:54] And mention in the scripture Ismail. He was truthful when he made a promise, and he was a messenger prophet.
(٥٤) وَاذْكُرْ فِي الْكِتَابِ إِسْمَاعِيلَ إِنَّهُ كَانَ صَادِقَ الْوَعْدِ وَكَانَ رَسُولًا نَبِيًّا
[19:55] He used to enjoin his family to observe the Contact Prayers (Salat) and the obligatory charity (Zakat); he was acceptable to his Lord.
(٥٥) وَكَانَ يَأْمُرُ أَهْلَهُ بِالصَّلَاةِ وَالزَّكَاةِ وَكَانَ عِنْدَ رَبِّهِ مَرْضِيًّا