Bhakti-rasāmṛta-sindhu .4.240
Blended reading (Sanskrit + English inline)
When Devakī, the mother of Kṛṣṇa, saw her son very jubilant in the presence of the wrestlers in Kaṁsa’s arena, two kinds of tears were simultaneously gliding down her cheeks: sometimes her tears were warm, and sometimes they were cold. This is an instance of a conjunction of jubilation and lamentation due to different causes of ecstatic love.
Gaja-danta-sphurad-aṁsam aṅgajam (seeing her son carrying the booty of an elephant tusk) is sometimes found instead of sutam utphulla-vilocanam purah (seeing her son with joyful eyes in front of her). Seeing her son victorious, her joy became prominent. In the case of the first version, for Devakī, who recognized her son as the Lord, seeing his joyful eyes acted as a stimulant and produced happiness. Thus both versions have a reasonable explanation.
My note
Source: vedabase.io