using a foul language, swearing, cursing and mocking others are hateful attributes. any decent person with a benevolent kind spirit would detest such shameful attitudes. the teacher should be a role model for his students who look up to him. if the teacher is characterized by one these negative attributes then it would be a major vice in his character. if the teacher possesses all those unpleasant traits, it would be a major disaster because students get affected by their teacher whether positively or negatively. if the teacher has such personality, what would we expect his students to be like?! the point is that cursing, uttering a foul language and mocking degrades and contaminates the nature of the human, it breaks the morale, corrupts the spirits and tongues and leads to mutual hostility etc. what was mentioned above is on one hand of the issue. on the other hand, what makes it even more serious is that those bad attitudes are religiously prohibited and their doers are sinners and deemed to be punished by almighty allah.

explanation:

1. mockery
2. almighty allah says: “o you who believe! let not a group scoff at another group, it may be that the latter are better than the former; nor let (some) women scoff at other women, it may be that the latter are better than the former, nor defame one another, nor insult one another by nicknames. how bad is it, to insult one's brother after having faith [i.e. to call your muslim brother (a faithful believer) as: "o sinner", or "o wicked", etc.]. and whosoever does not repent, then such are indeed zalimun (wrong-doers, etc.). (suratal-hujurat: 11). the words of allah “let not a group scoff at another group” means any kind of ridicule whether with words, actions or deeds that despise his muslim brother or fellow human. it is a sinful prohibited deed that most likely reflects self-admiration. mockery is an attitude that comes from a heart full of the worst manners and intentions and void of benevolence. the prophet muhammad (peace be upon him) said: “it is enough of evil for a person to hold his brother muslim in contempt. all of a muslim is inviolable to another muslim: his blood, his wealth and his honor.” (recorded by muslim: 2564)
3. cursing and abuse:
4. narrated by abdullah ibn-mas'oud: the prophet (pbuh) said, "abusing a muslim is fusuq (an evil doing) and killing him is kufr (disbelief)." (sahih al-bukhary, the book of faith, hadith number: 48). this hadith reinforces the right of a muslim of not to be insulted as anyone who does such act without a reason or right would be committing fusuq (depravity).

1. narrated by anas bin malik: the prophet (pbuh) was not one who would abuse (others) or say obscene words, or curse (others), and if he wanted to admonish anyone of us, he used to say: "what is wrong with him, his forehead be dusted!" (sahih al-bukhary, the book of good manners, hadith number: 6100)

1. narrated by abu’d-darda’: the prophet (pbuh) said, “the cursers will not be intercessors or witnesses on the resurrection day”. (sahih muslim, hadith number: 2598).

this is a proof of the punishment of an abuser or curser due to the massive negative consequences of their wrong doing. all what has been mentioned is enough evidence for those who have been granted sound understanding and judgment from almighty allah.

1. obscenity and foul language
2. narrated by abdullah ibn masoud: the prophet (pbuh) said, “a believer is not a slanderer, a curser, an abuser, nor an impudent man.” [recorded by at-tirmidhy (no. 1977) and corrected by al albani]

conclusion:

1. the above dispraised traits offend other people and hurt them.
2. mocking others is a kind of contempt and disrespect towards them. it causes animosity and hatred. if a teacher has such negative characteristic, it would be a shame.
3. cursing is a repulsive attitude and the consequence is punishment to the curser if he does not repent to allah. uttering a foul language proves a contaminated nature and an impure intention.