The Sunnah with regard to slaughter is to make the animal face towards the qiblah, but that is not obligatory. If he slaughters it facing any other direction, his slaughter is halaal, but he has omitted a Sunnah.
Ahmad (15022), Abu Dawood (2785) and Ibn Maajah (3121) narrated that Jaabir ibn ‘Abd-Allaah (may Allah be pleased with him) said: The Messenger of Allaah (blessings and peace of Allah be upon him) sacrificed two rams on the day of Eid. When he turned them to face towards the qiblah he said: “Verily, I have turned my face towards Him Who has created the heavens and the earth Haneefa (Islamic Monotheism, i.e. worshipping none but Allaah Alone), and I am not of Al-Mushrikoon .Verily, my Salaah (prayer), my sacrifice, my living, and my dying are for Allaah, the Lord of the ‘Aalameen (mankind, jinn and all that exists). He has no partner. And of this I have been commanded, and I am the first of the Muslims’ [cf. al-An’aam 6:79, 162-163]. O Allaah, from You and to You, on behalf of Muhammad and his ummah. In the name of Allah and Allah is most great.” Then he slaughtered them.
The isnaad of this hadeeth may reach the level of hasan as Shu’ayb al-Arna’oot said in Tahqeeq al-Musnad.
It says in al-Mawsoo’ah al-Fiqhiyyah (21/196), explaining the etiquette of slaughtering:
The slaughterer should face towards the qiblah and the animal’s neck should be turned to face the qiblah, because Ibn ‘Umar (may Allah be pleased with him) disliked eating the meat of any animal that had been slaughtered facing any direction other than the qiblah, and no one among the Sahaabah disagreed with him. That is narrated in some reports from Ibn Sireen and Jaabir ibn Zayd. End quote.
See: al-Mughni, 3/221
It says in Fataawa al-Lajnah al-Daa’imah (22/477) concerning one who slaughters an animal facing a direction other than the qiblah and claims that making it face the qiblah applies only when slaughtering the hadiy:
If the situation with regard to slaughter is as you say, then the slaughter is sound and valid in terms of it being halaal, but the slaughterer is going against the Sunnah by not turning to face the qiblah with the animal at the time of slaughter, and he is doing wrong by not accepting the advice, and he is mistaken in his claim that making it face the qiblah applies only when slaughtering the hadiy, because the Sunnah is to turn towards the qiblah with the animal at the time of slaughter in all cases, whether it is a hadiy or a sacrifice or otherwise. End quote.
It also says (1/67): It is mustahabb for the slaughterer to face towards the qiblah and to make the animal also face towards the qiblah, because it is the noblest of directions, and because turning to face the qiblah is mustahabb in acts of worship, except in cases where there is evidence to indicate otherwise. The fact that this is mustahabb is particularly emphasized if it is a hadiy or udhiyah. It is narrated from ‘Aa’ishah (may Allaah be pleased with her) that the Prophet (blessings and peace of Allaah be upon him) said: “Offer your sacrifices and be of good cheer, for there is no Muslim who turns his sacrifice to face the qiblah but its blood and dung and wool will be hasanaat that are present on his scales on the Day of Resurrection.” And he used to say: “Spend a little, you will be rewarded a great deal.” This hadeeth was narrated by ‘Abd al-Razzaaq in al-Musannaf, and al-Tirmidhi, Ibn Maajah and al-Bayhaqi narrated something similar. Although the imams of hadeeth suggested that its isnaad is weak, it may be acted upon with regard to encouraging good deeds. Hence Ibn ‘Umar and Ibn Sireen regarded it as makrooh to eat meat that was not facing the qiblah at the time of slaughter. Limiting oneself to saying Bismillaah and letting the animal face any direction at the time of slaughter is forsaking that which is better, but the slaughter is still valid. This was the view of al-Qaasim ibn Muhammad, al-Nakha’i, al-Thawri, Ibn al-Mundhir and others. End quote.
And Allaah knows best.