Frontinus, Stratagems 1.12.2
From a section on how to improve morale among your troops if they observe a bad omen.
C. Caesar, cum forte conscendens navem lapsus esset, ‘teneo te, terra mater,’ inquit. qua interpretatione effecit, ut repetiturus illas a quibus proficiscebatur terras videretur.
When Gaius Caesar had happened to slip as he was embarking on his ship, he said, ‘I hold you, mother earth!’ By this explanation he brought it about that it seemed he was going to return to those lands from which he was setting out.
Suetonius (The Divine Julius 59) has a different (and slightly better) version of the same story – or perhaps Caesar used the same tactic more than once!
prolapsus etiam in egressu navis, verso ad melius omine, ‘teneo te,’ inquit, ‘Africa.’
When he fell over as he was disembarking from his ship, he turned the omen to the better by saying ‘I hold you, Africa.’