Question: What are the sunan of the blessed 10 days of Zul Hijjah?
Answer: Those who are not performing Hajj and are at their own residence should observe some likeness of Hujjaj so that they can gain similar benefits of those Hujjaj.
It is stated in the hadith not to cut hair or nails: “Narrated ‘Umm Salama r.a. reported Allah’s Apostle (s.a.w) as saying: If anyone of you intends to offer sacrifice he should not get his hair cut or nails trimmed”.
References: [1] Muslim:1977 [2] Tirmizi:1528 [3] Abu Dawud:2791 [4] Nasai:4361 [5] Ibn Majah:3149
According to Hanafi fiqh it is Mustahab (desirable) not to cut hair or nails. Some Ahle Zahir (distinct sect) scholars and Imam Ahmed Ibn Hanble r.a regarded this as wajib. And some regard this as Mubah (permissible), neither its sunnah, wajib nor mustahab to them. Hanafi scholars states that this hukm (order of not cutting) is to adopt a likeness of the Hujjaj (those who are performing Hajj) because that time the Hujjaj don’t cut their hair and nails.
Therefore, those who did not go for Hajj at least adopt a likeness of the Hujjaj. And it is not illogical that whatever barakh Allah will bestow upon the Hujjaj, because of adopting a likeness of the Hujjaj Allah may bestow some barakah to them as well.
Reference: [1] Dars Tirmizi, vol-5 p-216. By Mufti Taqi Usmani D.B