'A'isha, the wife of the Messenger of Allah ﷺ, said Allah prescribed the prayer as two rak'ahs, then it was completed (to four rak'ahs) at the place of residence, but was retained in the same position in journey as it was first made obligatory.

أَنَّ عَائِشَةَ زَوْجَ النَّبِيِّ ﷺ قَالَتْ فَرَضَ اللَّهُ الصَّلاَةَ حِينَ فَرَضَهَا رَكْعَتَيْنِ ثُمَّ أَتَمَّهَا فِي الْحَضَرِ فَأُقِرَّتْ صَلاَةُ السَّفَرِ عَلَى الْفَرِيضَةِ الأُولَى

"The first time the Salah was enjoined it was two Rak'ahs, and it remained as such when traveling, but the Salah while resident was made complete."

أَوَّلَ مَا فُرِضَتِ الصَّلاَةُ رَكْعَتَيْنِ فَأُقِرَّتْ صَلاَةُ السَّفَرِ وَأُتِمَّتْ صَلاَةُ الْحَضَرِ

[AI] Al-Zuhri: How was the prayer of the Prophet ﷺ in Mecca before he migrated to Medina? He said: Urwah ibn Az-Zubair informed me that Aisha said, "Allah first ordained the prayer as two units, then completed it in Al-Hudaybiyah. The prayer of travel was established after the first obligation, and it was narrated from 'Amir Ash-Sha'bi from Masruq from Aisha."

الزُّهْرِيُّ كَيْفَ كَانَتْ صَلَاةُ النَّبِيِّ ﷺ بِمَكَّةَ قَبْلَ أَنْ يُهَاجِرَ إِلَى الْمَدِينَةِ؟ فَقَالَ أَخْبَرَنِي عُرْوَةُ بْنُ الزُّبَيْرِ عَنْ عَائِشَةَ قَالَتْ فَرَضَ اللهُ الصَّلَاةَ أَوَّلَ مَا فَرَضَهَا رَكْعَتَيْنِ ثُمَّ أَتَمَّهَا فِي الْحَضَرِ وَأُقِرَّتْ صَلَاةُ السَّفَرِ عَلَى الْفَرِيضَةِ الْأُولَى وَرُوِيَ عَنْ عَامِرٍ الشَّعْبِيِّ عَنْ مَسْرُوقٍ عَنْ عَائِشَةَ ؓ

"عَنْ عَائِشَةَ قَالَتْ: فَرَضَ اللهُ - تَعَالَى- آيَةَ الصَّلَاةِ أَوَّلَ مَا فَرَضَهَا رَكْعَتَيْنِ ثُمَ أَتَمَّهَا لِلْحَاضِرِ، وَأُقِرَّتْ صَلَاةُ السَّفَرِ عَلَى الفَرِيضَةِ الأُولَى".