Loyalty means to be faithful to ones duties (promises). Since loyalty is a word that we very often use, we tend not to dwell upon it much, however its importance in Islam can be shown by the following hadith from Prophet Muhammad (S):

Loyalty is part of the akhlaq that Islam has taught us, and to have loyalty makes a person higher (more dignified) in the eyes of Allah.
We know that the opposite of loyalty is betrayal. This is to break your promise, or let someone down. The Holy Prophet (S) has also said:

This shows that to control you tongue (speech) is an important part of loyalty, however, loyalty covers the performance of actions as well.
When you make a promise, then you are bound by it. Others are then relying on you, and you cannot let them down. If you are not sure that you can do what ever you said, then don't promise. Just say that you will try to do it.
People often make promises which they do not or cannot keep. What do you think are the reasons for this? Why do people make such promises. Can you think of some examples?
Yaqeen (Certainty):
We have discussed faith, and eiman. Yaqeen means to have certainty, to be sure, and it is a higher stage than eiman.
We are told that there is a God, have we seen Him ? When we read and learn, and when we are explained we get faith, and we believe that God then exists. Then we use our logic, we see that God must exist, we see His signs all around us, and we know through our intelligence that, yes there can only be one God, and He must exist. This is faith.
When we have faith, we then try harder to obtain Allah's pleasure, we talk to Him from our prayers, we talk to Him when we are in need, and if we are sincere enough, if we mean what we say, we will feel His answer. Allah will talk to us. He will not talk to our ears, but will talk directly to our hearts.
That is why when Imam Ali (A) was asked "Do you worship a God that you cannot see?" Imam Ali (A) replied "No, I would never worship something that I can not see. I see Allah with my heart, not with my mind."
This shows that when we reach the state of yaqeen, (Inshallah), we will know for a fact that Allah is there. We will have felt his presence everywhere, and we will be sure without doubt. Then Shaytan will not be able to put doubts in our head.
That is why Yaqeen is such a high stage. One which can only be reached with patience, and understanding.
