Does committing a sin twice make it major sin?

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

Persistence means to constantly perform an act. Returning to sin after repentance because of a weakness in determination and will is not considered as persisting in sin. A small sin repeated is not considered as a major sin except if one persists on it.

Imam Al Bukhari and Muslim reported that Abu Huraira narrated: "I heard the Prophet Muhammad () saying: "If somebody commits a sin and then says, 'O my Lord! I have sinned, please forgive me! 'and his Lord says, 'My slave has known that he has a Lord who forgives sins and punishes for them, I therefore have forgiven My slave (his sins). 'Then he remains without committing any sin for a while and then again commits another sin and says, 'O my Lord! I have committed another sin, please forgive me, 'and Allaah Says: "My slave has known that he has a Lord who forgives sins and punishes for them, I therefore have forgiven My slave (his sins). 'Then he remains without committing any other sin for a while and then commits other sin (for the third time) and says, 'O my Lord, I have committed another sin, please forgive me, ' and Allaah Says: "My slave has known that he has a Lord Who forgives sins and punishes for them. I therefore have forgiven My slave (his sins), he can do whatever he likes." The sentence of "He can do whatever he likes" means that Allaah will continue forgiving His slave as long as he continues asking Allaah's forgiveness."

Being persistent in committing a sin is disobedience in itself. 

Ibn al Qayyim stated that Ibn Jubair said that a man asked Ibn Abbas, may Allah be pleased with him, about major sins saying: "Are there only seven major sins?" Ibn Abbas replied:" There are up to 700, but there is no major sin with repentance, and there is no minor sin with persistence."

The questioner has to be cautious about three matters:

1)     A Mu'min should always feel that Allaah is watching him and seeing him. There is no doubt that if a person has this consciousness, he must avoid transgressing the limits of Allaah.

2)     A Mu'min must look to the seriousness of the sin, and to the greatness of the One who forbids it.

3)     The sinner finds committing more sins easy, and performing good deeds difficult even those that were easy for him before committing the sin.

Allaah knows best.