Luqman - 31:16
"My dear son, whether the weight of a grain of mustard seed is in a rock or in the heavens or in the earth, Allah will bring it. Allah is All-Loving, All-Knowing.
Allah brings forth a thing the weight of a grain of mustard seed:
The Prophets/21:47
We will set up scales of justice for the Day of Resurrection. No injustice will be done to anyone. We will take into account even the weight of a grain of mustard seed. We are sufficient as the reckoners.