Al-Hazhaz said that Sayyiduna Ibn Mas'ud (may Allah be pleased with him) held a severe view on kissing for the fasting person: that he should fast a day in its place. In our view, this applies when he kissed and ejaculated.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصيام / 8106