Lord Śrī Kṛṣṇa replied: My dear mother, I have never eaten dirt. All My friends complaining against Me are liars. If you think they are being truthful, you can directly look into My mouth and examine it.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
श्रीकृष्ण उवाच । नाहं भक्षितवानम्ब सर्वे मिथ्याभिशंसिनः । यदि सत्यगिरस्तर्हि समक्षं पश्य मे मुखम्
śrīkṛṣṇa uvāca | nāhaṃ bhakṣitavānamba sarve mithyābhiśaṃsinaḥ | yadi satyagirastarhi samakṣaṃ paśya me mukham
SB 10.8.35