Pundarika Charitam Vol III Book VIII Chp 1 Shlokas 4 - 5
केवलं धर्मममाश्रित्य रन्तिदेवादयः पुरा |
हरिं सन्तोषयामासुर्धर्मप्रियमनामयम् ||
अजोपि सन्नव्ययात्मा करोति जननं भुवि |
धर्मसंरक्षणायैव भगवान् धर्मवत्सलः ||
In the past, Rantideva and others pleased Lord Hari, who cherishes dharma, only with the help of strict adherence to dharma. Shri Bhagavan, who is beyond the cycle of births and deaths, takes birth (incarnate’s) on this earth in order to safeguard dharma as He is very interested in doing that.