Commentary for Berakhot 34:14

קברו את המת וחזרו אם יכולין להתחיל ולגמור עד שלא יגיעו לשורה יתחילו ואם לאו לא יתחילו

Having buried the dead and returned [from the grave], if they have sufficient time to begin and finish [the Shema'] before arriving at the row, they should commence it ; but if they have not sufficient time, they should not commence it.

Abraham Cohen Footnotes to the English Translation of Masechet Berakhot