Genesis 17  Abram is given a new name, Abraham, at the age of 99 when the Lord appears to him and establishes a covenant with him.  This covenant is different than any other.  First of all, it is and "everlasting" covenant.  It is a conditional covenant.  Abraham and his descendants were to "keep" the covenant by circumcising every male.  God's part of the covenant was to bless them, make them fruitful, and give them a land for their possession.  Although the Lord does command Abraham to "walk before" Him and to be "blameless", there does not appear to be any other conditions given to Abraham at this point.  
God also reveals the birth of Isaac which is to come and the fact that this covenant will be established through his line, not that of Ishmael.  Abraham and Sarah are past child bearing age at this point, so their natural response to this was to laugh.  God is not offended by this at all, in fact, He uses this to give a name to the promised son, Isaac, which means "he laughed".

Psalm 81  "...if you would only listen to Me!"   the Lord says to His people.  If we would only listen and obey, He would do mighty things.... subdue the enemy, punish the wicked, provide for every need, and satisfy every desire.  God is our strength,  He relieves our burdens,  He rescues us from trouble. But He commands us to have no "strange god"; to stop being stubborn and walking in our "own devices".  Listen to God.  Walk His ways.  Do what Abraham did, believe the promises and obey the commands.  Trust and obey.... the only way to be truly happy in Jesus!

Abba, Father,  I am listening and I will obey.  Have Your way in my life today. Amen