Why are the “salli” and “barik” prayers recited in the first sitting of the sunnah of the Asr prayer and the first…

According to the Hanafi school, except for the first sunnahs of the Dhuhr and Friday prayers, each two rak‘ahs of voluntary (nafl) prayers are considered as an independent prayer. Therefore, the first sittings are also regarded as the final sitting. For this reason, the “Salli” and “Barik” prayers are recited in the first sitting of the voluntary prayers performed before the obligatory (fard) prayers of Asr and Isha. For the same reason, after rising from the first sitting, the “Subhaneke” prayer is recited at the beginning of the next rak‘ah. (Bilmen, İlmihâl, 141-142)

Source: T.C. Diyanet İşleri Başkanlığı, Din İşleri Yüksek Kurulu