Yesterday I happened to come across a video which states about eating Desi Chicken and to keep it under personal observation for two or three days before slaughtering it as it eats what ever it finds including insects so it should be kept under observation and clean diet should be provided so that toxins are removed from meat as you eat. So I want to confirm about the authenticity of particular Hadith if any. I had done research but found nothing. Thanks in advance.
'Jallalah' is a category of animals that are generally halal to eat (eg, chickens) but then they eat filth thereby making it impermissible to eat them because as reported by Ibn Umar: "The Messenger of Allah (ﷺ) forbade the meat and milk of Al-Jallalah" - Ibn Majah (3189).
Does that make it impermissible to eat them forever? No. All you have to do is to end/remove the 'filth' from their diet and feed them pure foods again. It seems the '3 days/nights' concept is taken from the practice of Ibn Umar.
It says in Kashshaaf al-Qinaa‘ (6/193): (...) … (it is haraam) until it has been kept for three days and nights, because if Ibn ‘Umar wanted to eat (such an animal), he would keep it for three days and feed it with pure food, and prevent it from eating impure food, whether it was a bird or animal, because the factor that was preventing it from being halaal would be removed thereby. End quote.