What is the ruling on water present on the floor of a toilet/bathroom?
The default ruling is the purity of this water present on the bathroom floor. If one is certain or strongly suspects its impurity, then one washes whatever part of the body or clothing this impure water has touched. If one doubts its impurity, the default is purity, and we do not rule it impure based on mere doubt. And Allah the Almighty knows best.
What is the ruling on swearing a false oath by the Holy Quran?
Swearing a false oath by the Holy Quran dips the oath-taker in Hellfire, and one who had done so should turn to Allah in repentance, seek His forgiveness, give back rights to whom they belong, and pay the oath expiation.
I have a brother who is harsh in his dealings [with me], and many problems have occurred between us, and I do not intend to reconcile with him. What is the ruling of Islamic Law on that?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah.
It is not permissible for a Muslim to abandon or boycott his fellow Muslim brother for more than three days. This is based on the saying of the Messenger of Allah, peace and blessings be upon him: "It is not lawful for a Muslim to forsake his brother for more than three [days], meeting each other but one turns away and the other turns away, and the better of the two is the one who initiates the greeting (salam)." (Reported by al-Bukhari.)
A Muslim must strive to end such estrangement (hajr), so as not to fall under the prohibition mentioned in the hadith. If he takes the initiative to reconcile but the other party does not respond, then there is no sin upon him. We remind [ourselves] of the saying of Allah, the Exalted: "And let them pardon and overlook. Do you not wish that Allah should forgive you? And Allah is Forgiving and Merciful." (An-Nur/22). And Allah, the Exalted, knows best.
Is it permissible for a praying person to make supplication in each Sajdah (a prostration) of obligatory prayer?
It is permissible for a praying person, whether praying individually, or in congregation, to make supplication during Sujood (prostration) in obligatory, or voluntary prayers. However, it is disliked for the Imam to do so since he is required to spare the prayer performers any sort of hardship, unless he is leading a certain group who don`t mind him extending the prayer.