Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) says that the truce between the Prophet (peace and blessings be upon him) and the people of Makkah in the year of al-Hudaybiyyah was for 4 years.
Asim bin Umar bin Hafs al-Umari, who narrated it, is very da'if (weak). The preserved (mahfuz) report is the first one; this Asim bin Umar narrates things in which he is not corroborated, and Yahya bin Ma'in, al-Bukhari and other imams declared him weak.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجزية / 18810