Lovingkindness and Compassion of the Buddha?

In an effort to understand the concept of lovingkindness it would help me to see how the Buddha explicitly described lovingkindness and specific acts of his unconditional compassion. I've [heard]( https://dharmaseed.org/teacher/334/talk/7816/) from secondary sources that he'd throw out his "net" of compassion to walk 200 miles to teach someone, but I'm looking for **references** to primary or well known secondary (e.g. Bhikku Bodhi, Analayo) sources, please.