Those who love God must be patient.

 How long, O Lord, will you look on? Rescue me from their destruction, my precious life from the lions! I will thank you in the great congregation; in the mighty throng I will praise you. Let not those rejoice over me who are wrongfully my foes, and let not those wink the eye who hate me without cause. For they do not speak peace, but against those who are quiet in the land they devise words of deceit. They open wide their mouths against me; they say, "Aha, Aha! Our eyes have seen it!" You have seen, O LORD; be not silent! O Lord, be not far from me! Awake and rouse yourself for my vindication, for my cause, my God and my Lord! Vindicate me, O LORD, my God, according to your righteousness, and let them not rejoice over me! Let them not say in their hearts, "Aha, our heart's desire!" Let them not say, "We have swallowed him up." Let them be put to shame and disappointed altogether who rejoice at my calamity! Let them be clothed with shame and dishonor who magnify themselves against me! 

Psalm 35:17-23 (ESV)
 
AG Brown summarized how long we need to wait on the Lord.
 
1. "Long enough to try your faith." He loves to strengthen the faith of His people. Hence He often tries them by delaying the answers to their prayer.
2. "Long enough to teach you your own weakness."
3. To make you value the deliverance. That which is easily obtained is little valued. "Lord, how long wilt Thou look on?"
4. "Until the right moment." Not a moment too soon for His own glory: not a moment too late for your good.
 
Our clock is always too fast; we call upon the Lord and say, "Lord, now is the time; the hour to deliver has struck," but no answer comes because He keeps not His time by ours, and His clock still wants some minutes to the hour; but when that has struck, swift as the lightning flash He is at our side. Trust Him, then believe. Though it tarry, wait for it; because it will surely come. (A. G. Brown.)
 
Those who love God must be patient.