A person who is unable to bear another's distress is called compassionate.
Kṛṣṇa's compassion for distressed persons was exhibited when He released all of the kings imprisoned by Magadhendra. While dying, Grandfather Bhīṣma prayed to Kṛṣṇa and described Him as the sun which eradicated darkness. The kings imprisoned by Magadhendra were put into dark cells, and when Kṛṣṇa appeared there, the darkness immediately disappeared, just as if the sun had risen. In other words, although Magadhendra was able to imprison so many kings, upon the appearance of Kṛṣṇa they were all released. Kṛṣṇa released the kings out of His sincere compassion for them.
Kṛṣṇa's compassion was also exhibited when Grandfather Bhīṣma was lying on the bed of arrows which had been shot through his body. While lying in this position, Bhīṣma was very anxious to see Kṛṣṇa, and thus Kṛṣṇa appeared there. Upon seeing the pitiable condition of Bhīṣma, Kṛṣṇa began speaking with tears in His eyes. Not only was He shedding tears, but He also forgot Himself in His compassion. Therefore, instead of offering obeisances to Kṛṣṇa directly, devotees offer obeisances to His compassionate nature. Actually, because Kṛṣṇa is the Supreme Personality of Godhead, it is very difficult to approach Him. But the devotees, taking advantage of His compassionate nature, which is represented by Rādhārāṇī, always pray to Rādhārāṇī for Kṛṣṇa's compassion.