My father said, "The Prophet ﷺ used to prolong the first rakʿa of the Zuhr prayer and shorten the second one and used to do the same in the Fajr prayer."  

أَنَّ النَّبِيَّ ﷺ كَانَ يُطَوِّلُ فِي الرَّكْعَةِ الأُولَى مِنْ صَلاَةِ الظُّهْرِ وَيُقَصِّرُ فِي الثَّانِيَةِ وَيَفْعَلُ ذَلِكَ فِي صَلاَةِ الصُّبْحِ