He (God) never said to seek knowledge from cradle to grave

But to 

Seek wisdom from cradle to grave – Sayings of Muhammed (pbuh) 

Excess knowledge hampers spiritual progress 

Muhammed (pbuh) did not have knowledge (ilm) because he could neither read or write 

But 

He had wisdom (Hikma)

He who knows himself knows God) – Sayings of Muhammed

Knowledge is learnt externally 

Wisdom is gained internally