Meaning
Prostration; the act of worship, bowing the forehead to the ground.
How Iqbal uses it
One true, freely-given prostration to God liberates a man from a thousand servile bows to men. The sajda you think a burden is in fact what frees you.
See it in the verse
Sajda in Iqbal’s couplets
Ye ek sajda jise tu garaan samajhta hai
Hazaar sajdon se deta hai aadmi ko nijaat
Hazaar sajdon se deta hai aadmi ko nijaat
This one act of devotion, which you find so heavy to make — it frees a person from a thousand servile bowings.
Freedom · Selfhood
Kabhi ai haqeeqat-e-muntazir nazar aa libas-e-majaz mein
Ki hazaron sajde tarap rahe hain meri jabeen-e-niyaz mein
Ki hazaron sajde tarap rahe hain meri jabeen-e-niyaz mein
O long-awaited Truth, show yourself once in the dress of the visible — for a thousand prostrations are stirring restlessly on my brow of longing.
Love · Aspiration · Restlessness