What does it mean to dye poems and praise lambs?

"Ink sorrow and silk dyeing" comes from one of Du Fu's two Qujiang poems in Tang Dynasty, in which "Ink sorrow and silk dyeing" is used to describe the deep sadness of ink, as if it were dyed with silk thread. And "praising the lamb with poetry" means praising the purity and innocence of the lamb with poetry. The poet expressed his appreciation for the purity and innocence of the lamb through deep pen and ink and poetry.