It is narrated from Hasan (may Allah have mercy on him) that if a man says to his wife: "By Allah, I will not come to you tonight," and then leaves her for four months, then if he leaves her because of his oath, this is Ilaa (oath of abstention).
Hadith Referenceسنن سعید بن منصور / كتاب الطلاق / 3099
Hadith Takhrij«أخرجه سعيد بن منصور فى «سننه» ترقيم الدرالسلفية برقم:، 1922، وابن أبى شيبة فى «مصنفه» برقم: 18645، 18647»