“Offer prayer on time, and if you reached the Imam leading them in prayers (on time), then perform it with them, and you will be safe with your prayer, otherwise it will be voluntary for you.”  

عَنِ النَّبِيِّ ﷺ قَالَ صَلِّ الصَّلاَةَ لِوَقْتِهَا فَإِنْ أَدْرَكْتَ الإِمَامَ يُصَلِّي بِهِمْ فَصَلِّ مَعَهُمْ وَقَدْ أَحْرَزْتَ صَلاَتَكَ وَإِلاَّ فَهِيَ نَافِلَةٌ لَكَ  

[Machine] "For me, O Messenger of Allah ﷺ , pray the prayer on time. If you come to a group and they have already prayed, then you have safeguarded your prayer. But if they have not prayed, then you should pray with them, and it will be a voluntary prayer for you."  

لِي رَسُولُ اللَّهِ ﷺ «صَلِّ الصَّلَاةَ لِوَقْتِهَا فَإِنْ أَتَيْتَ الْقَوْمَ وَقَدْ صَلَّوْا كُنْتَ قَدْ أَحْرَزْتَ صَلَاتَكَ وَإِنْ لَمْ يَكُونُوا صَلَّوْا صَلَّيْتَ مَعَهُمْ وَكَانَتْ لَكَ نَافِلَةً»  

"صَلِّ الصَّلَاةَ لِوَقْتِهَا، فَإِنْ أَدْرَكْتَ مَعَهُمْ فَصَلِّ ولَا تَقُلْ إِنِّى قَدْ صَلَّيْتُ فَلَا أُصَلِّى".