One should be very careful not to swear, because there is no forgiveness for one who swears by something and then violates his words, Rabbi Yoshiyahu Pinto said in his last talk in the US.
He expanded on the fact that we see people saying “I swear by my parents” or “I swear by my children.” This is a very dangerous thing to say because our mouth and speech have great power. If we promise to do something - we must keep it.
"Whatever a person swears, and whatever vows a person accepts on himself - these are like warranties. The Holy One, blessed be He, will not forgive him for them if he doesn’t keep them," Rabbi Pinto added.
Watch his words:
Shuva Israel