ASAK.. If angels were already workshipping Allah , then why did Allah create humans and this universe, when he had angels already workshipping him...

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

There is no doubt that the angels worship their Lord and glorify Him night and day and they do not slacken to do so, and they obey His Orders and they do not disobey Him. Also, there is no doubt that Allaah created the jinn and the humankind to worship Him, and He bestowed on them whatever is in this universe in order to try and test them. Indeed, we have already issued Fataawa 88140 and 87212 clarifying this matter.

However, Allaah did not order them to worship Him due to a need or deficiency in Him; rather, Allaah does not need His Slaves to worship Him as the obedience of an obedient person does not benefit Him (Allaah) and the disobedience of a disobedient person does not harm Him. It is confirmed in a Qudsi Hadeeth that Allaah says: “O My Slaves, were the first of you and the last of you, the humans amongst you and the jinn amongst you to be as pious as the most pious heart of any man of you, that would not increase My domain a thing. O My slaves, were the first of you, and the last of you, the humans amongst you and the jinn amongst you to be as wicked as the most wicked heart of any man of you, that would not decrease My domain a thing.” [Muslim]

So whoever amongst the Slaves of Allaah obeys Him, his obedience is for the benefit of his own self, and whoever disobeys Him, his disobedience to Allaah is against his own self; it is for this reason that Allaah Says (what means): {Whoever is guided is only guided for [the benefit of] his soul. And whoever errs only errs against it.} [Quran 17:15]

At the end of the above Qudsi Hadeeth, Allaah says: “O My slaves, it is but your deeds that I reckon for you and then I recompense you for it, so let him who finds good (i.e. in the Hereafter) praise Allaah, and let him who finds other than that blame no one but himself.”

To conclude, Allaah created the human beings and He created the heavens and the earth so that Allaah would be known, worshipped Alone and obeyed; Allaah Says (what means): {It is Allaah who has created seven heavens and of the earth, the like of them. [His] command descends among them so you may know that Allaah is over all things competent and that Allaah has encompassed all things in knowledge.} [Quran 65:12]

Thus, Allaah has created all these so that His Slaves would know Him, know His Names and Attributes, and know that He is Perfect, and then they would worship Him without associating with him any partners.

Allaah Knows best.