Yes Cursing is a sin,you can politely convince him and say, you will not play if he curses,also it hurts Jesus ,as in Matthew 5:48 You, therefore, must be perfect, as your heavenly Father is perfect.
Matthew 12:36,37 I tell you, on the day of judgment men will render account for every careless word they utter; 37 for by your words you will be justified, and by your words you will be condemned.”
Wisdom 1:6-10 5 For a holy and disciplined spirit will flee from deceit,
and will rise and depart from foolish thoughts, and will be ashamed at the approach of unrighteousness.6 For wisdom is a kindly spirit and will not free a blasphemer from the guilt of his words; because God is witness of his inmost feelings, and a true observer of his heart, and a hearer of his tongue.7 Because the Spirit of the Lord has filled the world, and that which holds all things together knows what is said; 8 therefore no one who utters unrighteous things will escape notice, and justice, when it punishes, will not pass him by.9 For inquiry will be made into the counsels of an ungodly man,
and a report of his words will come to the Lord, to convict him of his lawless deeds;10 because a jealous ear hears all things, and the sound of murmurings does not go unheard.
James 3:9, 10 With it we bless the Lord and Father, and with it we curse men, who are made in the likeness of God. 10 From the same mouth come blessing and cursing. My brethren, this ought not to be so.