Abdullah bin Abbas reported,
Regarding the words of Allah Most High, "You who believe, do not violate the rites of Allah" [Maidah 5:2], the polytheists used to make pilgrimage to the Sacred House, offer sacrificial animals, honor the sanctity of the sacred sites, and conduct trade during their pilgrimage. The Muslims wanted to raid them, so Allah 
said, "Do not violate the rites of Allah" [Maidah 5:2].
Azami 12240
Hasanعن ابن عباس قال
قوله تعالى{يايها الذين امنوا لا تحلوا شعآىر الله} كان المشركون يحجون البيت الحرام، ويهدون الهدايا، ويعظمون حرمة المشاعر، ويتجرون في حجهم. فأراد المسلمون أن يغيروا عليهم، فقال الله عز وجل {لا تحلوا شعآىر الله}
No references are available.
Ibn Jareer Tabari narrated it in his Tafsir (8/22-23), from Muthanna, who said, Abu Salih informed us, who said, Muawiya bin Salih narrated to us, from Ali bin Abu Talha, from Ibn Abbas, and he related it.Its chain is hasan because of Abu Salih, who is Abdullah bin Salih, and Ali bin Abu Talha, for both of them make the hadith hasan.It has been said that its meaning is, do not treat as permissible what Allah has forbidden to you while you are in the state of ihram, based on the indication of His saying, the Exalted, "and when you have left the state of ihram, then hunt..." [Maidah 5:2]