Garudapurana 1.145.25

1.145.25

bhīṣmaḥ senāpatirabhūdādau dauryodhane bale /
pāṇḍavānāṃ śikhaṇḍī ca tayoryuddhaṃ babhūva ha /
śastrāśastri mahāghoraṃ dhasarātraṃ śarāśari //

Bhīṣma was the general at first in the army of Duryodhana,
and Śikhaṇḍin among the Pāṇḍavas; and between the two there was combat,
a hand-to-hand fight with weapons, exceedingly terrible, an exchange of arrows for ten days and nights.