It is in Bukhari

Does the sitting between two raka’ats ( Jilsatul Istiraha) have any authentic Hadith in Sunnah, i.e is it sunnah ? And can someone keep doing it in every prayer ?

Prayer | June 19, 2014 12:00 pm
Previous

I reached puberty at a very early age, and when I was younger I used to regularly miss Fajr or Isha Salah. (For a few years) .However when I got older I began to pray 5 times regularly Alhamdulillah. My question is, is it sufficient to pray 2 rakahs and seek forgiveness for those prayers or do I have to make them all up? This is a bit impractical as I do not know how many I missed.
Next

I would like to know that when we are praying in the mosque after one finishes his or her prayer can one cross the people behind who are praying their sunnah or nafl.because no one keeps a sutra.we have cross them to go out. Plz clarify.