'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 mother of believers: Allah enjoined the prayer when He enjoined it, it was two rakʿat only (in every prayer) both when in residence or on journey. Then the prayers offered on journey remained the same, but (the rakʿat of) the prayers for non-travelers were increased.
فَرَضَ اللَّهُ الصَّلاَةَ حِينَ فَرَضَهَا رَكْعَتَيْنِ رَكْعَتَيْنِ فِي الْحَضَرِ وَالسَّفَرِ فَأُقِرَّتْ صَلاَةُ السَّفَرِ وَزِيدَ فِي صَلاَةِ الْحَضَرِ
The prayer was prescribed as two rak'ahs, two rak'ahs both in journey and at the place of residence. The prayer while travelling remained as it was (originally prescribed), but an addition was made in the prayer (observed) at the place of residence.
عَنْ عَائِشَةَ زَوْجِ النَّبِيِّ ﷺ أَنَّهَا قَالَتْ فُرِضَتِ الصَّلاَةُ رَكْعَتَيْنِ رَكْعَتَيْنِ فِي الْحَضَرِ وَالسَّفَرِ فَأُقِرَّتْ صَلاَةُ السَّفَرِ وَزِيدَ فِي صَلاَةِ الْحَضَرِ
[Machine] Aisha, the wife of the Prophet ﷺ , said: Allah made the prayer obligatory by prescribing two units of prayer (raka'at) and then completed it for the people in the city, while maintaining the original obligation for travelers.
عَنْ عَائِشَةَ زَوْجِ النَّبِيِّ ﷺ قَالَتْ فَرَضَ اللهُ الصَّلَاةَ حِينَ فَرَضَهَا رَكْعَتَيْنِ ثُمَّ أَتَمَّهَا فِي الْحَضَرِ وَأُقِرَّتْ صَلَاةُ السَّفَرِ عَلَى الْفَرِيضَةِ الْأُولَى
"عَنْ عَائِشَةَ قَالَتْ: فَرَضَ اللهُ - تَعَالَى- آيَةَ الصَّلَاةِ أَوَّلَ مَا فَرَضَهَا رَكْعَتَيْنِ ثُمَ أَتَمَّهَا لِلْحَاضِرِ، وَأُقِرَّتْ صَلَاةُ السَّفَرِ عَلَى الفَرِيضَةِ الأُولَى".