Short answer
No. Swearing, cursing, lying and backbiting do not break wudu in any of the four schools, though they are sins. Hanafi scholars say it is recommended to renew wudu after them, since wudu washes away minor sins.
Speech does not break wudu, however bad it is. Renewing wudu after obscene speech, lying, backbiting and other sins is mustahabb.
The four schools agree on this.
Explanation
The things that break wudu (ablution) are physical: something leaving the body, losing consciousness, or deep sleep. Words, however bad, are not among them. So if you swore while driving, cursed in anger or let a lie slip, your wudu is still valid, and so is any prayer you pray with it.
That does not make the words light. The Prophet ﷺ said that whoever believes in Allah and the Last Day should say what is good or stay silent, and the Quran describes believers as those who turn away from ill speech. Cursing, obscene language and backbiting are sins that need sincere repentance, and an apology where a person was wronged.
What Hanafi scholars recommend:
- Renew your wudu after backbiting, lying, swearing or any other sin. It is mustahabb, not required.
- Say astaghfirullah, and replace the bad word with dhikr.
- If you swore during salah, the prayer is broken because ordinary speech breaks prayer, but your wudu is not.
Swearing in the sense of taking an oath, such as saying wallahi, does not break wudu either. The four schools agree on all of this. Related: music and wudu and laughing and wudu.
The evidence
Quran, Surah Al-Muminoon 23:3
وَٱلَّذِينَ هُمْ عَنِ ٱللَّغْوِ مُعْرِضُونَ ﴿٣﴾
And they who turn away from ill speech
Believers avoid bad speech, though it is not listed as a breaker of wudu.
Sahih al-Bukhari 6018
Sahih... من كان يؤمن بالله واليوم الآخر فليقل خيرا أو ليصمت ...
"Whoever believes in Allah and the Last Day, let him say what is good or stay silent."
Bad speech is a sin to repent from, separate from wudu.
Where the ruling is recorded
- Nur al-Idah with Maraqi al-Falah, Kitab al-Taharah, section on when wudu is recommended. Wudu is recommended after backbiting, lying and obscene speech.
- al-Hidaya, Kitab al-Taharat, section on what breaks wudu. The breakers are what leaves the body, loss of consciousness and laughter in prayer.
Checked by our team. For a more accurate answer to your own situation, consult a scholar. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.