Question about masturbation

I was talking to a brother today and he said that it is permissible to masturbate if one is in a difficult position..such as being with a women whom you may be attracted to and instead of committing zina.. it is permissible to masturbate just to get away from commiting zina?

Is this true.. first iv'e ever heard of it.. for all I know its haraam and there is a Hadith Shareef stating people whom do so.. there hands will be pregnant on the day of judgement?

please help jazak'Allah