We used not to call Zaid bin Haritha the freed slave of Messenger of Allah ﷺ except Zaid bin Muhammad till the Qu'anic Verse was revealed: "Call them (adopted sons) by (the names of) their fathers. That is more than just in the Sight of Allah." (33.5)  

أَنَّ زَيْدَ بْنَ حَارِثَةَ مَوْلَى رَسُولِ اللَّهِ ﷺ مَا كُنَّا نَدْعُوهُ إِلاَّ زَيْدَ ابْنَ مُحَمَّدٍ حَتَّى نَزَلَ الْقُرْآنُ {ادْعُوهُمْ لآبَائِهِمْ هُوَ أَقْسَطُ عِنْدَ اللَّهِ}  

The Prophet ﷺ sent an army under the command of Usama bin Zaid. When some people criticized his leadership, the Prophet ﷺ said, "If you are criticizing Usama's leadership, you used to criticize his father's leadership before. By Allah! He was worthy of leadership and was one of the dearest persons to me, and (now) this (i.e. Usama) is one of the dearest to me after him (i.e. Zaid).  

بَعَثَ النَّبِيُّ ﷺ بَعْثًا وَأَمَّرَ عَلَيْهِمْ أُسَامَةَ بْنَ زَيْدٍ فَطَعَنَ بَعْضُ النَّاسِ فِي إِمَارَتِهِ فَقَالَ النَّبِيُّ ﷺ إِنْ تَطْعُنُوا فِي إِمَارَتِهِ فَقَدْ كُنْتُمْ تَطْعُنُونَ فِي إِمَارَةِ أَبِيهِ مِنْ قَبْلُ وَايْمُ اللَّهِ إِنْ كَانَ لَخَلِيقًا لِلإِمَارَةِ وَإِنْ كَانَ لَمِنْ أَحَبِّ النَّاسِ إِلَىَّ وَإِنَّ هَذَا لَمِنْ أَحَبِّ النَّاسِ إِلَىَّ بَعْدَهُ