وَجَاءَتِ الطَّائِفَةُ الْأُولَى، فَصَلَّوْا وُحْدَانًا رَكْعَةً وَسَجْدَتَيْنِ بِغَيْرِ قِرَاءَةٍ، وَتَشَهَّدُوا وَسَلَّمُوا
Translation: The first group returns and each person individually completes one rakah and its two prostrations without recitation, then says tashahhud and salam.
The first group began with the imam but temporarily left to guard. In Hanafi analysis it is comparable to the lahiq, a follower who completes what was missed while still legally bound to the imam’s earlier prayer.
That is why the remaining rakah is completed without personal recitation, as the explicit phrase bi-ghayri qiraah states.