Even earlier than "I Contain Multitudes," one can find allusions to Whitman's poetry in Dylan's lyrics:
https://bob-dylan.org.uk/archives/5670
"In a number of his song lyrics, Dylan makes reference to Walt Whitman’s poetry:
All swims before her eyes, flashes with black, she
catches the main words only
Sentences broken, ‘gunshot wound in the breast, cavalry
skirmish, taken to hospital
At present low, but soon will be better ….
While they stand at the home at the door he is dead already
(Walt Whitman: Come Up From The Fields Father)
Below again, a connection to the American Civil War:
A letter came to to mother
Came today
Gunshot wound to the breast
Is what it did say
But he’ll be better soon
He’s in a hospital bed
But he’ll never be better
He’s already dead
(Bob Dylan: ‘Cross The Green Mountain)"