What is the ruling of Islamic Law on saying the basmalah at the beginning of wudu`?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah.
Saying the basmalah (Bismillāh) at the beginning of wuḍūʾ is a sunnah. It is stated in al-Minhāj al-Qawīm Sharḥ al-Muqaddimah al-Ḥaḍramiyyah (p. 27): “Its sunnahs include the siwāk, then the tasmiyah (saying Bismillāh), joined with the intention (niyyah), at the start of washing the hands.” And Allah Almighty knows best.
Does passing wind, from the anus without a smell, invalidate prayer?
If a person is certain of having passed wind even if it was with no smell, then both his/her ablution and prayer are invalidated, thus he/she should remake ablution and re-perform prayer.
Which hour coincides with the last third of the night?
This hour could be figured out by calculating the number of night hours which start at sunset, and end at dawn break, then the total is divided on three to get the result.
Is it correct that everything dry is pure even if it has impurity on it?
If something impure becomes dry, it remains impure and is not purified by drying. However, the impurity does not transfer by touching it if the one touching it is also dry. And Allah the Almighty knows best.