SB 10.81.1-2

śrī-śuka uvāca
sa itthaṁ dvija-mukhyena
 saha saṅkathayan hariḥ
sarva-bhūta-mano-’bhijñaḥ
 smayamāna uvāca tam
brahmaṇyo brāhmaṇaṁ kṛṣṇo
 bhagavān prahasan priyam
premṇā nirīkṣaṇenaiva
 prekṣan khalu satāṁ gatiḥ
Word for word: 
śrī-śukaḥ uvāca — Śukadeva Gosvāmī said; saḥ — He; ittham — in this manner; dvija — of brāhmaṇas; mukhyena — with the best; saha — together; saṅkathayan — conversing; hariḥ — Lord Hari; sarva — of all; bhūta — living beings; manaḥ — the minds; abhijñaḥ — who knows perfectly; smayamānaḥ — smiling; uvāca — said; tam — to him; brahmaṇyaḥ — devoted to the brāhmaṇas; brāhmaṇam — to the brāhmaṇa; kṛṣṇaḥ — Lord Kṛṣṇa; bhagavān — the Supreme Personality of Godhead; prahasan — laughing; priyam — at His dear friend; premṇā — lovingly; nirīkṣaṇena — with a glance; eva — indeed; prekṣan — looking; khalu — indeed; satām — of the saintly devotees; gatiḥ — the goal.
Translation: 
[Śukadeva Gosvāmī said:] Lord Hari, Kṛṣṇa, perfectly knows the hearts of all living beings, and He is especially devoted to the brāhmaṇas. While the Supreme Lord, the goal of all saintly persons, conversed in this way with the best of the twice-born, He laughed and spoke the following words to that dear friend of His, the brāhmaṇa Sudāmā, all the while smiling and looking upon him with affection.
Purport: 

According to Śrīla Śrīdhara Svāmī, the words sarva-bhūta-mano-’bhijña indicate that since Lord Kṛṣṇa knows the minds of everyone, He could tell at once that His friend Sudāmā had brought some flat rice for Him and was ashamed to present it. According to Śrīla Viśvanātha Cakravartī’s further explanation of this verse, Lord Kṛṣṇa smiled at this moment, thinking “Yes, I am going to make you show what you brought for Me.” His smile then turned to laughter as He thought, “How long are you going to keep this precious gift hidden in your cloth?”

Kṛṣṇa glanced toward the bundle hidden inside His friend’s garment, telling Sudāmā by His loving glance, “The veins showing through your emaciated skin and your ragged clothes astonish everyone present, but these symptoms of poverty will last only until tomorrow morning.”

Although Lord Kṛṣṇa is Bhagavān, the supreme, independent Lord, He is always pleased to reciprocate with those who are priya, His cherished servants. As the indulgent patron of the brāhmaṇa class, He especially enjoys favoring brāhmaṇas who are additionally qualified by unconditional devotion to Him.