Surah Yunus, Ayat 60-61

Ayat 60. And what think those who invent lies against Allah, on the Day of Resurrection? [i.e. Do they think that they will be forgiven and excused! Nay, they will have an eternal punishment in the Fire of Hell]. Truly, Allah is full of Bounty to mankind, but most of them are ungrateful.

Ayat

61. Whatever you (O Muhammad  [SAWW](PBUH) may be doing, and whatever portion you may be reciting from the Qur'an, - and whatever deed you (mankind) may be doing (good or evil), We are Witness thereof, when you are doing it. And nothing is hidden from your Lord (so much as) the weight of an atom (or small ant) on the earth or in the heaven. Not what is less than that or what is greater than that but is (written) in a Clear Record. 

Hazrat Ibn `Abbas (May Allah be pleased with them) reported: The Messenger of Allah  [SAWW](PBUH) said to Jibril (Gabriel), "What prevents you from visiting us more frequently?'' Thereupon was revealed the Ayah: "(The angels say:) `And we (angels) descend not except by the Command of your Rubb. To Him belongs what is before us and what is behind us, and what is between those two". (19[Surah Maryam]: Ayat64)

[Al-Bukhari Volume 6, Book 60, Hadith Number 255]. 

Lesson : as mentioned above in Surah Yunus Ayat 61. "And nothing is hidden from your Lord (Allah SWT)?" This Hadith tells us about the Prophet's  [SAWW](PBUH) desire for meeting angel Jibril (Gabriel) to have that knowledge which was revealed to him by means of Wahy (Revelation of Al-Quran). It also tells us that angels descend to earth for certain mission by the Command of Allah. They have no say of their own in any matter. It also indicates that it is permissible to enquire about Muslim brothers after a long period of time as this is a sign of true love.