Reference: Siyar A’laam an-Nubalaa – Volume 5, Page 189
Sulaym ibn ‘Aamir said:
I entered upon al-Jarraah, and he raised his hands, and [likewise] the leaders [around him too] raised their hands – and they remained [like this] for a long while. He (al-Jarraah) then said to me:
O Abaa Yahyaa, do you know what we were doing (supplicating for)?
I replied: No; I found you all intensely engaged [in supplication], so I raised my hands [in supplication] with you all.
He (al-Jarraah) said: We asked Allaah to bless us with martyrdom.
And by Allaah, none of them remained in that battle until each one of them attained martyrdom.