Reference: http://www.alfawzan.af.org.sa/node/16237
Question: What is the ruling about eating the meat which was slaughtered by someone who was ignorant of the [prescribed] Sunnah [manner of slaughter]?
Response: So long as he is a Muslim – testifying there is none [truly] worthy of worship except Allaah [alone], and that Muhammad is the Messenger of Allaah, and he does not associate any partners [in worship] with Allaah – then [in this case] his slaughter is halaal. [Allaah (Azza wa Jall) says]:
{So eat of that [meat] upon which the name of Allaah has been mentioned, if you are believers in His verses}, soorah al-An’aam, aayah 118
So the slaughter [carried out] by a Muslim is halaal, even if he forgot to utter ‘bismillaah’; certainly it is halaal because [the utterance of] ‘bismillaah’ is [firm] in his heart as well as his ‘aqeedah.
