If we don't forgive our fellow humans we can also receive forgiveness from God,look at God's word we were commanded to forgive the sins committed against us so we can also be forgiven by God,lack of forgiveness denies you access into God's kingdom but the moment you forgive all wrongs done against you,certainly you are in the right path
Lack of Forgiveness can stand as an hindrance from receiving blessings from God if you refuse to let go,harboring grudges with a stony heart is wickedness.