[19].Surah Maryam [Mary] : Ayat 64-65

Ayat 64. And we (angels) descend not except by the Command of your Lord (O Muhammad [SAWW](PBUH). To Him belongs what is before us and what is behind us, and what is between those two, and your Lord is never forgetful,

Ayat 65. Lord of the heavens and the earth, and all that is between them, so worship Him (Alone) and be constant and patient in His worship. Do you know of any who is similar to Him? (of course none is similar or coequal or comparable to Him, and He has none as partner with Him). [There is nothing like unto Him and He is the All-Hearer, the All-Seer].

[Tafseer] We are apt to be impatient of the evils we see around us. We may give of our best service to Allah, and yet see no results. In our human short-sightedness we may complain within ourselves. But we must not be impatient. The angels of Grace come not haphazardly, but by command of Allah according to His Universal Will and Purpose. Allah does not forget. If things are delayed, it is in accordance with a wise providence, which cares for all. Our plain duty is to be patient and constant in His service.  The more we taste of the truth and mystery of life, the more do we realise that there is no one to be mentioned in the same breath as Allah. He is above all names. But when we think of His beautiful qualities, and picture them to ourselves by names which give us some ideas of Him, we can search the whole wide world of our imagination, and we shall not find another to be compared with Him in name or quality. He is the One: praise be to Him! 

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". (19:64)

[Al-Bukhari Book 06,Chapter 60, Hadith # 255] 

Lesson : as mentioned above in Surah Maryam Ayat 64."And we (angels) descend not except by the Command of your Lord" This Hadith tells us about the Prophet's desire for meeting angel Jibril (Gabriel) to have that knowledge which was revealed to him by means of Wahy (Revelation). 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.