Why does the Almighty God grant intercession of His saints?

Iranian thinker Murteza Motahhari in response to this question says: “The Act of God has an order. If someone ignores the order of creation he has gone astray. This is why the Almighty God has guided the sinful to go to the residence of His Prophet (PBUH) and seek forgiveness of God in addition for seeking the Prophet’s intercession: “And if, when they wronged themselves, they had come to you, [O Muhammad], and asked forgiveness of Allah and the Messenger had asked forgiveness for them, they would have found Allah Accepting of repentance and Merciful.” (Surah Nisa: 64)(1)
The Act of God in expanding and increasing the means of offering His Mercy and Forgiveness for the sinful creatures is based on His Justice and Grace. As such, it is the Will of God to grant the advantage of intercession to the messengers and the saints of Allah to venerate them. Acceptance of worship and the beseeching of the God’s saints to the Almighty God is to venerate the saints. God’s saints and friends, people of good nature, the heavenly angels and the Messengers of the Firmament who have spent all their lives serving Allah, never trespassing what they have been ordained to, deserve veneration. And what veneration is above and better than granting their request of pardoning for the servants who deserve the Mercy and Forgiveness of God at the Almighty’s permission? The Almighty God addresses His Messenger and says: “it is expected that your Lord will resurrect you to a praised station.” (Surah Isra: 79)
In conclusion, it is clear that the issue of intercession, as a rational and logical principle, is so firm and valid that no claim on contradiction or disclaim, raised in areas of perceptions and wisdoms can find a flaw in this theory and make it invalid. This is because proper understanding and acceptance of this principle will show that it leaves no flaw on the monotheistic beliefs and it has no contradiction with the Divine justice. And finally, The Act of God in expanding and increasing the means of gaining His Mercy and Forgiveness for the sinful creatures is based on His Justice and Grace.