How did the Prophet, peace and blessings be upon him, treat the Companions, the hypocrites, and the disbelievers? Did he smile and show kindness to everyone, or only to believers? And how should a Muslim deal with non-Muslims or hypocrites at university according to the Sunnah and the Book of Allah?

The Prophet, peace and blessings be upon him, treated people with good character and gentleness, even those with whom he disagreed religiously or morally. This is in accordance with Allah's saying: "And indeed, you are upon a tremendous character." (Quran 68:4) It is legislated for a student to treat their peers with good and gentle conduct, while adhering to love for Allah and hatred for His sake, and loyalty to His allies and disavowal of His enemies. As for mudaraah (conciliation), it is permissible; it means gentle speech and refraining from harshness. It differs from the forbidden mudahanah (flattery/compromising principles), which means befriending the wicked and not denouncing their actions. Severity and harshness are required towards disbelievers when fighting them, but for those who are not fighting, kindness and beneficence are legislated towards them.