Srimad Bhagavatam

References to text SB 1.3.28
SB 1.3.28: All of the above-mentioned incarnations are either plenary portions or portions of the plenary portions of the Lord, but Lord Śrī Kṛṣṇa is the original Personality of Godhead. All of them appear on planets whenever there is a disturbance created by the atheists. The Lord incarnates to protect the theists.

Text №
O my friend, please, therefore, chant the glories of the Lord, who is meant to be glorified in the places of pilgrimage. He is unborn, and yet He appears by His causeless mercy upon the surrendered rulers of all parts of the universe. Only for their interest did He appear in the family of His unalloyed devotees the Yadus.
Questions by Vidura
SB 3.1.45
Dear Lord, we offer our respectful obeisances unto You because Your existence is completely independent of all material influences. Your Lordship always takes away the devotee’s miserable conditions, for Your brain plans how to do so. You live everywhere as Paramātmā; therefore You are known as Vāsudeva. You also accept Vasudeva as Your father, and You are celebrated by the name Kṛṣṇa. You are so kind that You always increase the influence of all kinds of devotees.
The Activities of the Pracetas
SB 4.30.24
My Lord, Your form is transcendental to the three material modes, yet for the maintenance of the three worlds, You assume the white color of Viṣṇu in goodness; for creation, which is surrounded by the quality of passion, You appear reddish; and at the end, when there is a need for annihilation, which is surrounded by ignorance, You appear blackish.
The Birth of Lord Krishna
SB 10.3.20
O Nanda Mahārāja, as recorded in history, when there was an irregular, incapable government, Indra having been dethroned, and people were being harassed and disturbed by thieves, this child appeared in order to protect the people and enable them to flourish, and He curbed the rogues and thieves.
Lord Krishna Shows the Universal Form Within His Mouth
SB 10.8.17
Śrī Nārada said: I offer my obeisances to Him of spotless fame, the Supreme Lord Kṛṣṇa, who manifests His all-attractive personal expansions so that all living beings can achieve liberation.
The Prayers of the Personified Vedas
SB 10.87.46