Sunnah.com reference : Book 7, Hadith 41English translation : Book 7, Hadith 0Arabic reference : Book 7, Hadith 814
Muslim has:
"He has three days in which to decide to keep them or not."
وَلِمُسْلِمٍ: { فَهُوَ بِالْخِيَارِ ثَلَاثَةَ أَيَّامٍ }   1‏ .‏‏1 ‏- مسلم ( 1524 )‏ ( 24 )‏.‏