"God is great," this rebel soldier says. "You will drink out of our bitter glass."
It is one of the boldest attacks on the capital by opposition forces in several years.
They were targeting areas where they had seized control at the weekend before being forced to retreat.
The surprise attack reportedly began with car and suicide bombings, before fighters from a wide mix of groups infiltrated the long-held government area through underground tunnels.
The intense fighting came on the eve of new peace talks in the Swiss city of Geneva.
The United Nations' Syria mediator, Staffan de Mistura, has called on the warring sides to prepare for substantive political discussions at week-long negotiations which start tomorrow.
A UN spokeswoman in Geneva, Alessandra Vellucci, has laid out the aims of the talks.
"The Special Envoy urged the invitees in his Security Council briefing, and in all contacts since the conclusion of the Round 4 to do the necessary preparations in advance of the fifth round to be ready to engage substantively and proactively on the substance of all four baskets on the agenda in parallel. The agenda of the talks, gathered by Resolution 2254, 2015, will focus on governance, constitutional issues, elections and counter-terrorism, security and confidence building measures."
Syrian government and opposition delegations to the fourth round last month have confirmed they will attend.
Mr De Mistura has travelled to the Saudi Arabian capital Riyadh and is also visiting the Russian and Turkish capitals for consultations ahead of the talks.
Meanwhile, the war, now beginning its seventh year, rages on.
President Bashar al-Assad, supported by the Russian military and Iranian-backed militias, is seeking to press his advantage and inflict total defeat on his opponents.
