Meaning
Endurance, the power to bear; also heat, glow, radiance.
Literally: Strength to endure; also the burning glow, as in tab-o-taab (heat and brilliance).
How Iqbal uses it
Taab plays on its double sense of endurance and burning radiance; Iqbal exploits the link between the heart's capacity to bear and the fire (aab-o-taab) that gives the self its glow.
See it in the verse
Taab in Iqbal’s couplets
Ahval-e-mohabbat mein kuch farq nahin aisa
Soz o tab-o-taab avval soz o tab-o-taab aakhir
Soz o tab-o-taab avval soz o tab-o-taab aakhir
In the states of love there is no real difference — the same burning and restless glow at the start, the same burning and restless glow at the end.
Love · Restlessness · Self-Knowledge
Mire khaak o khun se tu ne ye jahan kiya hai paida
Sila-e-shahid kya hai tab-o-tab-e-javedana
Sila-e-shahid kya hai tab-o-tab-e-javedana
From my dust and my blood you have brought this world into being; and the reward of the one who gives himself is an everlasting glow.
Selfhood · Action · Aspiration
Isi kashmakash mein guzrin meri zindagi ki raaten
Kabhi soz-o-saz-e-rumi kabhi pech-o-tab-e-razi
Kabhi soz-o-saz-e-rumi kabhi pech-o-tab-e-razi
The nights of my life passed in this very struggle: now the fire and harmony of Rumi, now the restless reasoning of Razi.
Love · Self-Knowledge · Restlessness