Is it permissible to recite aloud during the Prayer of Need (Salat al-Hajah) and the Prayer of Seeking Guidance (Salat al-Istikharah) at night, and is it permissible to seek forgiveness (istighfar) or supplicate (du'a) during their prostration or in other places of supplication, regardless of whether the supplications are related to the subject of the two prayers or not?

It is prescribed to recite aloud in the prayers of Istikharah (guidance) and Hajah (need) for those who perform them at night. It is also prescribed to supplicate (make du'a) in prostration (sujud) and other places of supplication in both obligatory and supererogatory prayers, whether the supplication is related to the prayer or not. Similarly, seeking forgiveness (istighfar) is prescribed during prostration in these two prayers, as the Prophet, peace and blessings be upon him, frequently used to say: "Glorified be You, O Allah, our Lord, and with Your praise, O Allah, forgive me," and he would say: "O Allah, forgive me all my sins: its minor and major, its first and last, its apparent and secret."