Friday is called Al-Jumu`ah

بسم الله الرحمن الرحيم

الحمد الله ربَّ العالمين، وصلى الله وسلم على نبيه محمد و على آله وسلم تسليمًا كثيرًا مزيدًا.
أما بعد

Friday is called Al-Jumu`ah because it is derived from Al-Jam`, literally, gathering. The people of Islam gather weekly, on every Friday in the major places of worship. It was during Friday when Allah finished the creation, the sixth day, during which Allah created the heavens and earth. During Friday, Allah created Adam, and he was placed in Paradise, and ironically, it was a Friday when he was taken out of Paradise. It will be on a Friday when the Last Hour will commence. There is an hour during Friday, wherein no faithful servant asks Allah for something good, but Allah will give him what he asked for. All of this is based upon Hadiths in the authentic collections. In the ancient language Friday was called, `Arubah. It is a fact that previous nations were informed about Friday, but they were led astray from it. The Jews chose Saturday for their holy day, but Adam was not created on Saturday. The Christians chose Sunday, which is the day the creation was initiated. Allah chose Friday for this Ummah, because it is the day the creation was finished .Al-Bukhãri and Muslim recorded that Abu Hurayrah said that the Messenger of Allah said,

«نَحْنُ الْاخِرُونَ السَّابِقُونَ يَوْمَ الْقِيَامَةِ، بَيْدَ أَنَّهُمْ أُوتُوا الْكِتَابَ مِنْ قَبْلِنَا، ثُمَّ إِنَّ هَذَا يَوْمَهُمُ الَّذِي فَرَضَ اللهُ عَلَيْهِمْ فَاخْتَلَفُوا فِيهِ فَهَدَانَا اللهُ لَهُ، فَالنَّاسُ لَنَا فِيهِ تَبَعٌ، الْيَهُودُ غَدًا وَالنَّصَارَى بَعْدَ غَدٍ»

(We are the last (to come) but the first on the Day of Resurrection, though the former nations were given the Scriptures before us. And this was their day (Friday) the celebration of which was made compulsory for them, but they differed about it. So, Allah gave us guidance to it, and all other people are coming after us: the Jews tomorrow and the Christians the day after tomorrow.''

This is the wording of Al-Bukhãri in another narration of Muslim;

«أَضَلَّ اللهُ عَنِ الْجُمُعَةِ مَنْ كَانَ قَبْلَنَا، فَكَانَ لِلْيَهُودِ يَوْمُ السَّبْتِ، وَكَانَ لِلنَّصَارَى يَوْمُ الْأَحَدِ، فَجَاءَ اللهُ بِنَا فَهَدَانَا اللهُ لِيَوْمِ الْجُمُعَةِ، فَجَعَلَ الْجُمُعَةَ وَالسَّبْتَ وَالْأَحَدَ، وَكَذَلِكَ هُمْ تَبَعٌ لَنَا يَوْمَ الْقِيَامَةِ نَحْنُ الْاخِرُونَ مِنْ أَهْلِ الدُّنْيَا، وَالْأَوَّلُونَ يَوْمَ الْقِيَامَةِ الْمَقْضِيُّ بَيْنَهُمْ قَبْلَ الْخَلَائِقِ»

(Allah diverted those who were before us from Friday. For the Jews there was Saturday, and for the Christians there was Sunday. Allah then brought us and guided us to Friday. He made them; Friday, Saturday and Sunday, and it is in this order they will come after us on the Day of Resurrection. We are the last of among the people of this world and the first among the created to be judged on the Day of Resurrection.)

Taken from Surah al-Juma'ah Ibn Kathir