Ruling on offering Salat-ul-Kusuf during the times wherein it is permissible to perform Salah only if there is a Shar`y reason
On Friday morning, Rabi` Al-Thany, there was a total lunar eclipse after Fajr (Dawn) Prayer. Some Imams (the ones who lead congregational Prayer) offered Salat-ul-Khusuf (Prayer at the time of a lunar eclipse), and others refused arguing that praying (a supererogatory Salah) after Fajr Prayer is impermissible.
Please, clarify the ruling on this for me!
Salat-ul-Kusuf (Prayer at the time of a solar eclipse) is one of the Salahs (Prayers) performed for specific reasons. According to the preponderant opinion, Salahs which have reasons are excluded from the times when it is not permissible to offer supererogatory Salah, meaning that one can pray those Salahs at these times. Thus, the prohibition is only applied to those Salahs which do not have particular causes. Based on this, if, for example, a solar eclipse happens after `Asr (Afternoon) Prayer, it is permissible for Muslims to pray Salat-ul-Kusuf along with Dhikr (Remembrance of Allah), Istighfar (seeking forgiveness from Allah), and Sadaqah (voluntary charity). By the same token, if a lunar eclipse happens after the break of dawn, it is permissible to offer Salat-ul-Khusuf because the apparent meaning of the evidence indicates this and because the light of the moon is not totally obscured. But in the case of offering Salat-ul-Kusuf before Fajr Prayer, it is better not to prolong it lest the time for Fajr Prayer becomes tight.